International Space Station
Overview
 
The International Space Station (ISS) is a habitable, artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 in low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

. The ISS follows the Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

, Almaz
Almaz
The Almaz program was a series of military space stations launched by the Soviet Union under cover of the civilian Salyut DOS-17K program after 1971....

, Cosmos
Cosmos 557
Kosmos 557 was the designation given to DOS-3, the next space station in the Salyut program. It was originally intended to be launched as Salyut-2, but due to its failure to achieve orbit on May 11, 1973, three days before the launch of Skylab, it was renamed Kosmos-557.Due to errors in the flight...

, Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, and Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space stations, as the 11th space station launched, not including the Genesis
Genesis II
Genesis II is a 1973 American TV film created and produced by Gene Roddenberry and directed by John Llewellyn Moxey.It opens with the line, "My name is Dylan Hunt...

 I and II prototypes. The ISS serves as a research laboratory that has a microgravity environment in which crews conduct experiments in many fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, human biology
Human biology
Human Biology is an interdisciplinary area of study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, epidemiology, ecology, nutrition, population genetics and sociocultural influences. It is closely related to...

, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. The station has a unique environment for the testing of the spacecraft systems that will be required for missions to the Moon and Mars.
Encyclopedia
The International Space Station (ISS) is a habitable, artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 in low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

. The ISS follows the Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

, Almaz
Almaz
The Almaz program was a series of military space stations launched by the Soviet Union under cover of the civilian Salyut DOS-17K program after 1971....

, Cosmos
Cosmos 557
Kosmos 557 was the designation given to DOS-3, the next space station in the Salyut program. It was originally intended to be launched as Salyut-2, but due to its failure to achieve orbit on May 11, 1973, three days before the launch of Skylab, it was renamed Kosmos-557.Due to errors in the flight...

, Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, and Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space stations, as the 11th space station launched, not including the Genesis
Genesis II
Genesis II is a 1973 American TV film created and produced by Gene Roddenberry and directed by John Llewellyn Moxey.It opens with the line, "My name is Dylan Hunt...

 I and II prototypes. The ISS serves as a research laboratory that has a microgravity environment in which crews conduct experiments in many fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, human biology
Human biology
Human Biology is an interdisciplinary area of study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, epidemiology, ecology, nutrition, population genetics and sociocultural influences. It is closely related to...

, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. The station has a unique environment for the testing of the spacecraft systems that will be required for missions to the Moon and Mars. The station is expected to remain in operation until at least 2020, and potentially to 2028. Russia's next planned space station OPSEK
Orbital Piloted Assembly and Experiment Complex
The Orbital Piloted Assembly and Experiment Complex ' is the planned Russian successor to the International Space Station, with the main goal of supporting deep space exploration.-Overview:...

, is to be separated prior to the ISS's deorbit to form a new, separate space station, intended to support deep space exploration. Like many artificial satellites, the ISS can be seen from Earth with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...

. The ISS is operated by Expedition crews, and has been continuously staffed since 2 November 2000—an uninterrupted human presence in space for the past . , the crew of Expedition 29
Expedition 29
Expedition 29 was the 29th long-duration expedition to the International Space Station . The expedition formally began with the departure from the ISS of the Soyuz TMA-21 spacecraft at 00:38 UTC on on 16 September 2011...

 is aboard.

The ISS combines the Japanese Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 laboratory with three space station projects, the Soviet/Russian Mir-2
Mir-2
Mir-2 was a space station project begun in February 1976. Some of the modules built for Mir-2 have been incorporated into the International Space Station . The project underwent many changes, but was always based on the DOS-8 base block space station core module, built as a back-up to the DOS-7...

, the American Freedom
Space Station Freedom
Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after...

, and the European Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

. Budget constraints led to the merger of these projects into a single multi-national programme. The ISS is a third generation modular space station, comparable to MIR, OPSEK and Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

, consisting of pressurised modules, external trusses, solar arrays and other components which have been launched by Russian Proton rockets, American space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

s, and Russian Soyuz rockets. The station is maintained in orbit between 278 km (173 mi) and 460 km (286 mi) altitude, and travels at an average ground speed
Ground speed
Ground speed is the speed of an aircraft relative to the ground. Information displayed to passengers through the entertainment system often gives the aircraft groundspeed rather than airspeed....

 of 27,724 km (17,227 mi) per hour, completing 15.7 orbits per day.

The ISS is a joint project between the five participating space agencies, the American NASA, the Russian RKA
Russian Federal Space Agency
The Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...

, the Japanese JAXA
Japan Aerospace Exploration Agency
The , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...

, the European ESA
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

, and the Canadian CSA. The ownership and use of the space station is established in intergovernmental treaties and agreements which divide the station into two areas and allow the Russian Federation to retain full ownership of Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS)/(RS), with the US Orbital Segment
US Orbital Segment
The US Orbital Segment is the name given to the components of the International Space Station constructed and operated by the US National Aeronautics and Space Administration , European Space Agency , Canadian Space Agency and Japan Aerospace Exploration Agency .The segment currently consists of...

 (USOS) allocated between the other international partners. The station is serviced by Soyuz spacecraft, Progress spacecraft, the Automated Transfer Vehicle
Automated Transfer Vehicle
The Automated Transfer Vehicle or ATV is an expendable, unmanned resupply spacecraft developed by the European Space Agency . ATVs are designed to supply the International Space Station with propellant, water, air, payload and experiments...

 and the H-II Transfer Vehicle
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

, and has been visited by astronauts and cosmonauts from 15 different nations.

Purpose

According to the original Memorandum of Understanding between NASA and RSA, the International Space Station was intended to be a laboratory, observatory and factory in space. It was also planned to provide transportation, provide servicing and act as a staging base for possible future missions to the Moon, Mars and asteroids. In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic, and educational purposes.

Scientific research

The ISS provides a platform to conduct scientific research that cannot be performed in any other way. While unmanned spacecraft can provide platforms for zero gravity and exposure to space, the ISS offers a long term environment where studies can be performed potentially for decades, combined with ready access by human researchers over periods that exceed the capabilities of manned spacecraft. Kibō is intended to accelerate Japan's progress in science and technology, gain new knowledge and apply it to such fields as industry and medicine. The Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 (AMS), which NASA compares to the Hubble telescope, could not be accommodated on a free flying satellite platform, due in part to its power requirements and data bandwidth needs. The Station simplifies individual experiments by eliminating the need for separate rocket launches and research staff.
The primary fields of research include Space weather
Space weather
Space weather is the concept of changing environmental conditions in near-Earth space or thespace from the Sun's atmosphere to the Earth's atmosphere. It is distinct from the concept ofweather within the Earth's planetary atmosphere...

, human research, space medicine
Space medicine
Space medicine is the practice of medicine on astronauts in outer space whereas astronautical hygiene is the application of science and technology to the prevention or control of exposure to the hazards that may cause astronaut ill health. Both these sciences work together to ensure that...

, life sciences, physical science
Physical science
Physical science is an encompassing term for the branches of natural science and science that study non-living systems, in contrast to the life sciences...

s, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. Scientists on Earth have access to the crew's data and can modify experiments or launch new ones; benefits generally unavailable on unmanned spacecraft. Crews fly expeditions of several months duration, providing approximately 160 man-hours a week of labor with a crew of 6.

Research on the ISS improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy
Muscle atrophy
Muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass...

, bone loss
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...

, and fluid shift. This data will be used to determine whether lengthy human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....

 and space colonization
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...

 are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars
Manned mission to Mars
A manned mission to Mars has been the subject of science fiction, engineering, and scientific proposals throughout the 20th century and into the 21st century...

.
Medical studies are conducted aboard the ISS on behalf of the National Space and Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity
Advanced Diagnostic Ultrasound in Microgravity
The Advanced Diagnostic Ultrasound in Microgravity Project is a US Government funded study investigating strategies for applying diagnostic telemedicine to space. The Principal Investigator is Scott Dulchavsky, Chairman of Surgery at the Henry Ford Health System...

 study in which astronauts perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.

Microgravity

Gravity is the only significant force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

 acting upon the ISS, which is in constant freefall
Free fall
Free fall is any motion of a body where gravity is the only force acting upon it, at least initially. These conditions produce an inertial trajectory so long as gravity remains the only force. Since this definition does not specify velocity, it also applies to objects initially moving upward...

. This state of freefall, or perceived weightlessness, is not perfect however, being disturbed by four separate effects: One, the drag resulting from the residual atmosphere, when the ISS enters the Earth's shadow, the main solar panels are rotated to minimize this aerodynamic drag, helping reduce orbital decay
Orbital decay
Orbital decay is the process of prolonged reduction in the altitude of a satellite's orbit.This can be due to drag produced by an atmosphere due to frequent collisions between the satellite and surrounding air molecules. The drag experienced by the object is larger in the case of increased solar...

. Two, vibration caused by mechanical systems and the crew on board the ISS. Three, orbital corrections by the on-board gyroscopes or thrusters. Four, the spatial separation from the real centre of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

 of the ISS. Any part of the ISS not at the exact center of mass will tend to follow its own orbit
Gravity-gradient stabilization
Gravity-gradient stabilization is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and the Earth's gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction...

. That is, parts on the underside, closer to the Earth are pulled harder, towards the Earth. Conversely, parts on the top of the station, further from Earth, try to fling off into space. However, as each point is physically part of the station, this is impossible, and so each component is subject to small forces which keep them attached to the station as it orbits. This is also called the tidal force
Tidal force
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...

.

Researchers are investigating the effect of the station's near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate microgravity's effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.

The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour of fluids better. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding of superconductivity
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

.

The study of materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...

 is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

s, ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, water vapour
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

, and oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

s in Earth's atmosphere, as well as cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s, cosmic dust
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...

, antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

, and dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 in the universe.

Exploration

The ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will be required for long-duration missions to the Moon and Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

. This provides experience in the maintenance, repair, and replacement of systems on-orbit, which will be essential in operating spacecraft farther from Earth. Mission risks are reduced, and the capabilities of interplanetary spacecraft are advanced. The ESA states that "Whereas the ISS is essential for answering questions concerning the possible impact of weightlessness, radiation and other space-specific factors, other aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations".

A Mars exploration mission may be a multinational effort involving space agencies and countries outside the current ISS partnership. In 2010 ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other 4 partners that China, India and South Korea be invited to join the ISS partnership. NASA chief Charlie Bolden stated in Feb 2011 "Any mission to Mars is likely to be a global effort". As of 2011, the space agencies of Europe, Russia and China carried out the ground-based preparations in the Mars500 project, which complement the ISS-based preparations for a manned mission to Mars. China launched its own space station in September 2011, and has officially initiated its programme for a modular station. However, China has indicated a willingness to cooperate further with other countries on manned exploration.

Education and cultural outreach

The ISS crew provide opportunities for students on Earth by running student-developed experiments, making educational demonstrations, allowing for student participation in classroom versions of ISS experiments, and directly engaging students using radio, videolink and email. Cultural activities are another major objective. There is something about space that touches even people who are not interested in science.

Amateur Radio on the ISS (ARISS) is a volunteer programme which inspires students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

 communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from 9 countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.

JAXA aims both to 'Stimulate the curiosity of children, cultivating their spirits, and encouraging their passion to pursue craftsmanship', and to 'Heighten the child's awareness of the importance of life and their responsibilities in society.' Through a series of education guides, a deeper understanding of the past and near-term future of manned space flight, as well as that of Earth and life, will be learned. In the JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISS is explored. Students grow sunflower seeds which flew on the ISS for about nine months as a start to ‘touch the Universe’. In the first phase of kibo utilization from 2008 to mid-2010, researchers from more than a dozen Japanese universities conducted experiments in diverse fields.

ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms. In one lesson, students can navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.

First Orbit
First Orbit
First Orbit is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker...

 is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker Christopher Riley and ESA astronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital space flight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced from the Russian State Archive. Nespoli, during Expedition 26/27, filmed the majority of the footage for this documentary film, and as a result is credited as its director of photography
Cinematographer
A cinematographer is one photographing with a motion picture camera . The title is generally equivalent to director of photography , used to designate a chief over the camera and lighting crews working on a film, responsible for achieving artistic and technical decisions related to the image...

. The film was streamed through the website www.firstorbit.org in a global YouTube
YouTube
YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....

 premiere in 2011, under a free license.

Origins

The International Space Station represents a combination of three national space station projects, NASA's Freedom, the RSA's Mir-2, and the European Columbus space stations. In September 1993, American Vice-President Al Gore, Jr., and Russian Prime Minister Viktor Chernomyrdin
Viktor Chernomyrdin
Viktor Stepanovich Chernomyrdin was the founder and the first chairman of the Gazprom energy company, the longest serving Prime Minister of Russia and Acting President of Russia for a day in 1996. He was a key figure in Russian politics in the 1990s, and a great contributor to the Russian...

 announced plans for a new space station, which eventually became the International Space Station. They also agreed, in preparation for this new project, that the United States would be involved in the Mir programme, including American Shuttles docking, in the Shuttle-Mir Program
Shuttle-Mir Program
The Shuttle–Mir Program was a collaborative space program between Russia and the United States, which involved American Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the shuttle and an American astronaut flying aboard a Soyuz spacecraft to engage in...

. According to the plan, the International Space Station programme would combine the proposed space stations of all participant agencies and the Japanese Kibō laboratory.

NASA's Freedom

In the early 1980s, NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 planned to launch a modular space station called Freedom as a counterpart to the Soviet Salyut and Mir space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...

s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, "We can follow our dreams to distant stars, living and working in space for peaceful economic and scientific gain", Freedom was never constructed or completed as originally designed, and after several cutbacks, the remnants of the project became part of the ISS. Several NASA Space Shuttle missions in the 1980s and early 1990s included spacewalks to demonstrate and test space station construction techniques.

NASA's first cost assessment in 1987 revealed the 'Dual Keel' Station would cost $14.5 billion. This caused a political uproar in Congress, and NASA and Reagan Administration officials reached a compromise in March 1987 which allowed the agency to proceed with a cheaper $12.2-billion Phase One Station that could be completed after 10 or 11 Shuttle assembly flights. This design initially omitted the $3.4-billion 'Dual Keel' structure and half of the power generators. The new Space Station configuration was named 'Freedom' by Reagan in June 1988. Originally, Freedom would have carried two 37.5 kW solar arrays. However, Congress quickly insisted on adding two more arrays for scientific users. The Space Station programme was plagued by conflicts during the entire 1984-87 definition phase. In 1987, the Department of Defense (DoD) briefly demanded to have full access to the Station for military research, despite strong objections from NASA and the international partners. Besides the expected furor from the international partners, the DoD position sparked a shouting match between Defense Secretary Caspar Weinberger and powerful members of Congress that extended right up to the final Fiscal 1988 budget authorization in July 1987. Reagan wanted to invite other NATO countries to participate in the U.S-led project, since the Soviet Union had been launching international crews to their Salyut space stations since 1971. At one point, then-anonymous disgruntled NASA employees calling themselves "Center for Strategic Space Studies" suggested that instead of building Freedom, NASA should take the back-up Skylab from display in the National Air and Space Museum in Washington and launch that.

The space station was also going to tie the emerging European and Japanese national space programmes closer to the U.S.-led project, thereby preventing those nations from becoming major, independent competitors too. An agreement signed in September 1988 allocated 97% of the US lab resources to NASA while the Canadian CSA would receive 3% in return for its contribution to the programme. Europe and Japan would retain 51% of their own laboratory modules. Six Americans and two international astronauts would be permanently based on Space Station Freedom.

Russia's Mir-2

The Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS or RS) is the eleventh Soviet-Russian space station. Mir and the ISS are successors to the Salyut and Almaz stations. Mir-2 was originally authorized in the February 1976 resolution setting forth plans for development of third generation Soviet space systems. The first MIR-2 module was launched in 1986 by an Energia
Energia
Energia was a Soviet rocket that was designed by NPO Energia to serve as a heavy-lift expendable launch system as well as a booster for the Buran spacecraft. Control system main developer enterprise was the NPO "Electropribor"...

 heavy-lift expendable launch system. The launcher worked properly, however the Polyus payload fired its engines to insert itself into orbit whilst in the wrong position due to a programming error, and re-entered the atmosphere. The planned station changed several times, but Zvezda was always the service module. The station would have used the Buran
Buran
Buran may refer to:* Buran , a Soviet space shuttle** Buran program, which developed the spacecraft* Buran eavesdropping device, invented by Léon Theremin, used by soviet intelligence* Buran cruise missile, a Soviet cruise missile...

 space shuttle and Proton rockets to lift new modules into orbit. The spaceframe of Zvezda, also called DOS-8 serial number 128, was completed in February 1985 and major internal equipment was installed by October 1986.

The Polyus module or spacecraft, which would have served the same function as Zarya, looked like a "Salyut" slightly modified for this task and was made up from parts of the ships "Cosmos-929, -1267, -1443, -1668" and from modules of MIR-2 station. There are two different descriptions of the weapon systems. In one, Polyus is described as a space-borne nuclear bomber, in another it is described as a satellite interceptor, carrying a 1 MegaWatt carbon dioxide laser. The module had a length of almost 37 m and a diameter of 4.1 m weighed nearly 80 t and included 2 principal sections, the smallest, the functional service block (FGB) and the largest, the aim module.

In 1983, the design was changed and the station would consist of Zvezda, followed by several 90 metric ton modules and a truss structure similar to the current station. The draft was approved by NPO Energia Chief Semenov on 14 December 1987 and announced to the press as 'Mir-2' in January 1988. This station would be visited by the Russian Space Shuttle Buran, but mainly resupplied by Progress-M2 spacecraft. Orbital assembly of the station was expected to begin in 1993. In 1993 with the collapse of the Soviet Union, a redesigned smaller Mir-2 was to be built whilst attached to Mir, just as OPSEK is being assembled whilst attached to the ISS.

Japan's Kibō

Conceived in 1985, the Japanese Experiment Module (JEM) or Kibō consists of a pressurized laboratory mainly dedicated to advanced technology experiments, a logistics module, an unpressurized pallet for vacuum experiments in space plus a robotic arm. While the proposed space station was redesigned many times around Kibō, the only significant change has been additional ballistic shielding, as its final position at the front of the station increases the risk of damage from debris. The Japanese National Space Development Agency (NASDA) formally submitted the JEM proposal to NASA in March 1986.

In 1986 the Japanese contribution was estimated to be worth $1.9-3.2 billion for a JEM launch in 1995. By 1990, the schedule had slipped by three years due to NASA budget cuts and space station cost overruns. The delays increased the JEM's total cost slightly, from $2.3 billion in 1986 to $2.63 billion in 1993, when the launch was postponed to 1999. Final hardware production began in the mid-1990s and the Japanese robotic arm was tested on a NASA Space Shuttle flight in August 1997. According to plans prior to the Columbia disaster, the JEM would be launched in 2002-03.
In 2010, Kibō won the Good Design Award, a year old consumer and industry award which identifies the best of Japanese craftsmanship. During August 2011, an observatory mounted on Kibō, which utilizes the ISS's orbital motion to image the whole sky in the X-ray spectrum, detected for the first time the moment a star was swallowed by a black hole.

ESA's Columbus

The Columbus Man-Tended Free Flyer (MTFF) was a European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 (ESA) programme to develop a space station that could be used for a variety of microgravity experiments while serving ESA's needs for an autonomous manned space platform. The programme ran from 1986 to 1991, was expected to cost $3.56 billion including launch and utilization, and was cancelled while still in the planning stage. Aspects of the programme were later realised in the Columbus module.

In November 1992, further financial difficulties in Russia and uncertainties with America's Freedom space station led Russia and the European Space Agency to open discussions on joint development and use of Mir-2.

Station structure

The ISS is a 'third generation' or modular space station. Other examples of modular station projects include the Soviet/Russian MIR, Russian OPSEK, and Chinese Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

. The first space station, Salyut 1
Salyut 1
Salyut 1 was the first space station of any kind, launched by the USSR on April 19, 1971. It was launched unmanned using a Proton-K rocket. Its first crew came later in Soyuz 10, but was unable to dock completely; its second crew launched in Soyuz 11 and remained on board for 23 days...

, and other one-piece or 'monolithic' first generation space stations, such as Salyut 2,3,4,5, DOS 2, Kosmos 557, Almaz and NASA's Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

 stations were not designed for re-supply. Each crew had to depart the station to free the only docking port for the next crew to arrive. Second generation station projects such as Salyut 6 and 7 feature a second docking port. Third generation stations are modular stations, this allows the mission to be changed over time, new modules can be added or removed from the existing structure, saving considerable costs and allowing greater flexibility.

Below is a diagram of major station components. The blue areas are pressurized sections accessible by the crew without using spacesuits. The station's unpressurized superstructure is indicated in red. Other unpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.


Assembly

The assembly of the International Space Station, a major endeavour in space architecture
Space architecture
Space architecture, in its simplest definition, is the theory and practice of designing and building inhabited environments in outer space. The architectural approach to spacecraft design addresses the total built environment, drawing from diverse disciplines including physiology, psychology, and...

, began in November 1998. Russian modules launch and dock robotically, with the exception of Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

. All other modules were delivered by space shuttle, which required installation by ISS and shuttle crewmembers using the SSRMS and EVAs; , they had added 159 components during more than 1,000 hours of EVA activity. 127 of these spacewalks originated from the station, while the remaining 32 were launched from the airlocks of docked space shuttles. The beta angle
Beta angle
The beta angle is a value that is used most notably in spaceflight. The beta angle determines the percentage of time an object such as a spacecraft in low Earth orbit spends in direct sunlight, absorbing solar energy. Beta angle is defined as the angle between the orbit plane and the vector from...

 of the station had to be considered at all times during construction, as the station's beta angle is directly related to the percentage of its orbit that the station (as well as any docked or docking spacecraft) is exposed to the sun; the space shuttle would not perform optimally above a limit called the "beta cutoff". Rassvet was delivered by NASA's Atlantis Space Shuttle in 2010 in exchange for the Russian Proton delivery of the United States-funded Russian-built Zarya Module in 1998. Robot arms rather than EVAs were utilized in its installation (docking).

The first segment of the ISS, Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

, was launched on 20 November 1998 on an autonomous Russian Proton rocket. It provided propulsion, orientation control, communications, electrical power, but lacked long-term life support functions. Two weeks later a passive NASA module Unity was launched aboard Space Shuttle flight STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 and attached to Zarya by astronauts during EVAs. This module has two Pressurized Mating Adapter
Pressurized Mating Adapter
The International Space Station uses three Pressurized Mating Adapters to interconnect spacecraft and modules with different docking mechanisms. The first two PMAs were launched with the Unity module in 1998 aboard STS-88...

s (PMAs), one connects permanently to Zarya, the other allows the space shuttle to dock to the space station. At this time, the Russian station Mir was still inhabited. The ISS remained unmanned for two years, during which time Mir was de-orbited. On July 12, 2000 Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive vehicle for a rendezvous with the Zarya and Unity. As a passive "target" vehicle, the Zvezda maintained a stationkeeping orbit as the Zarya-Unity vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. Zarya's computer transferred control of the station to Zvezda's computer soon after docking. Zvezda added sleeping quarters, a toilet, kitchen, CO2 scrubbers, dehumidifier, oxygen generators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.

The first resident crew, Expedition 1
Expedition 1
Expedition 1, or Expedition One, was the first long-duration stay on the International Space Station . The three-person crew stayed aboard the station for 136 days, from November 2000 to March 2001. It was the beginning of an uninterrupted human presence on the station which still continues, as of...

, arrived in November 2000 on Soyuz TM-31
Soyuz TM-31
Soyuz TM-31 was the first Soyuz spacecraft to dock with the International Space Station . Launched near the end of 2000 the Soyuz-TM spacecraft brought to ISS Expedition 1, the first long-duration ISS crew...

, midway between the flights of STS-92
STS-92
STS-92 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Discovery. STS-92 marked the 100th mission of the Space Shuttle...

 and STS-97
STS-97
STS-97 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Endeavour. The crew installed the first set of solar arrays to the ISS, prepared a docking port for arrival of the Destiny Laboratory Module, and delivered supplies for the station's crew.-Crew:-Mission...

. These two Space Shuttle flights each added segments of the station's Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

, which provided the station with Ku-band communication for U.S. television, additional attitude support needed for the additional weight of the USOS, and substantial solar arrays supplementing the station's existing 4 solar arrays.

Over the next two years the station continued to expand. A Soyuz-U
Soyuz-U
The Soyuz-U launch vehicle is an improved version of the original Soyuz LV. Soyuz-U is part of the R-7 family of rockets based on the R-7 Semyorka missile. Members of this rocket family were designed by the TsSKB design bureau and constructed at the Progress Factory in Samara, Russia....

 rocket delivered the Pirs docking compartment. The Space Shuttles Discovery, Atlantis
Space Shuttle Atlantis
The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...

, and Endeavour delivered the Destiny laboratory and Quest airlock, in addition to the station's main robot arm, the Canadarm2, and several more segments of the Integrated Truss Structure.

The expansion schedule was interrupted by the destruction of the on STS-107
STS-107
-Mission parameters:*Mass:**Orbiter Liftoff: **Orbiter Landing: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 90.1 min- Insignia :...

 in 2003, with the resulting hiatus in the Space Shuttle program
Space Shuttle program
NASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...

me halting station assembly until the launch of Discovery on STS-114
STS-114
-Original crew:This mission was to carry the Expedition 7 crew to the ISS and bring home the Expedition 6 crew. The original crew was to be:-Mission highlights:...

 in 2005.

The official resumption of assembly was marked by the arrival of Atlantis, flying STS-115
STS-115
Note:The P3/P4 Truss segment and batteries were so heavy that the crew count was reduced from seven to six.-Crew notes:...

, which delivered the station's second set of solar arrays. Several more truss segments and a third set of arrays were delivered on STS-116
STS-116
-Crew notes:Originally this mission was to carry the Expedition 8 crew to the ISS. The original crew was to be:-Mission highlights:* The STS-116 mission delivered and attached the International Space Station's third port truss segment, the P5 truss....

, STS-117
STS-117
- Crew Notes :The initial crew manifest before the Columbia accident was:Astronaut Mark Polansky was originally slated to pilot this mission, but was moved to STS-116, which he commanded...

, and STS-118
STS-118
- Crew notes :Astronaut Clayton Anderson originally was slated to be launched to the ISS on this mission, but was moved to STS-117. His replacement was Alvin Drew....

. As a result of the major expansion of the station's power-generating capabilities, more pressurised modules could be accommodated, and the Harmony node and Columbus European laboratory were added. These were followed shortly after by the first two components of Kibō. In March 2009, STS-119
STS-119
-Crew notes:This mission was originally scheduled to bring the Expedition 9 crew to the ISS. This crew would have consisted of:-Mission parameters:* Mass:* Orbiter liftoff: * Orbiter landing: * Perigee: * Apogee:...

 completed the Integrated Truss Structure with the installation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009 on STS-127
STS-127
STS-127 was a NASA Space Shuttle mission to the International Space Station . It was the twenty-third flight of . The primary purpose of the STS-127 mission was to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility , and the Exposed Section of the...

, followed by the Russian Poisk module. The third node, Tranquility, was delivered in February 2010 during STS-130
STS-130
STS-130 was a NASA Space Shuttle mission to the International Space Station . 's primary payloads were the Tranquility module and the Cupola, a robotic control station with six windows around its sides and another in the center, providing a 360-degree view around the station...

 by the Space Shuttle Endeavour, alongside the Cupola, closely followed in May 2010 by the penultimate Russian module, Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

, delivered by Space Shuttle Atlantis on STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

. The last pressurised module of the USOS, Leonardo, was brought to the station by Discovery on her final flight, STS-133
STS-133
STS-133 was the 133rd mission in NASA's Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discoverys 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011...

, followed by the Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 on STS-134
STS-134
STS-134 was the penultimate mission of NASA's Space Shuttle program. The mission marked the 25th and final flight of . This flight delivered the Alpha Magnetic Spectrometer and an ExPRESS Logistics Carrier to the International Space Station. Mark Kelly served as the mission commander...

, delivered by Endeavour.

, the station consisted of fifteen pressurised modules and the Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

. Still to be launched are the Russian Multipurpose Laboratory Module Nauka and a number of external components, including the European Robotic Arm
European Robotic Arm
The European Robotic Arm is a robotic arm to be attached to the Russian Segment of the International Space Station. It will be the first robot arm able to work on the Russian space station segments, and will supplement the two Russian Strela cargo cranes that are already installed on the Pirs...

. Assembly is expected to be completed by 2012, by which point the station will have a mass in excess of 400 metric tons (440 short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s).

The gross mass of the station is not possible to calculate with precision. The total launch weight of the modules on orbit is 417289 kilogram (as of 03/09/2011). The weight of experiments, spare parts, personal effects, crew, foodstuff, clothing, propellants, water supplies, gas supplies, docked spacecraft, and other items add to the total mass of the station. Gas (Hydrogen) is constantly vented overboard by the Oxygen generators.

Pressurised modules

Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

 , also known as the Functional Cargo Block or FGB , was the first module of the station, launched on November 20, 1998 on a Russian Proton rocket from Baikonur Cosmodrome Site 81
Baikonur Cosmodrome Site 81
Site 81 at the Baikonur Cosmodrome is a launch site used, along with Site 200, by Proton rockets. It consists of two launch pads, areas 23 and 24. Area 24 is currently used for Proton-K and Proton-M launches, while Area 23 is currently inactive....

 in Kazakhstan to a 400 km (248.5 mi) high orbit. After parking in orbit, the Zarya Module provided orientation control, communications and electrical power for itself, and for the passive Node 1 (Unity) attached later, while the station awaited launch of the third component, a Russian-provided crew living quarters and early station core, the service module Zvezda. The Service Module enhanced or replaced many functions of Zarya. The FGB is a descendant of the TKS spacecraft
TKS spacecraft
TKS spacecraft was a Soviet spacecraft design in the late 1960s intended to supply the military Almaz space station. The spacecraft was designed for manned or autonomous cargo resupply use...

 designed for the Russian Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

 programme. 6,100 kg of propellant fuel can be stored and transferred automatically to and from ships docked to the Russian portion of the station – the Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS). Zarya was originally intended as a module for the Russian Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space station, but was not flown as of the end of the Mir-1 programme. Development costs for Zarya were paid for by Russia (and the former Soviet Union), spread across previous space station programmes, and some construction and preparation costs were paid for by the United States. Unity, a passive connecting module was the first U.S.-built component of the Station. It is cylindrical in shape, with six berthing locations facilitating connections to other modules. Unity was carried into orbit as the primary cargo of STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 in 1998.

Zvezda , DOS-8, also known as the Service Module or SM . It provides all of the station's critical systems, its addition rendered the station permanently habitable for the first time, adding life support for up to six crew and living quarters for two. Zvezda's DMS-R computer handles guidance, navigation & control for the entire space station. A second computer which performs the same functions is installed in the Nauka FGB-2. The rocket used for Zvezda's launch was one of the first to carry advertising
Space advertising
Space advertising is the use of advertising in outer space or related to space flight. While there have only been a few examples of successful marketing campaigns, there have been several proposals to advertise in space, some even planning to launch giant billboards visible from the Earth...

. The space frame was completed in February 1985, major internal equipment was installed by October 1986, and it was launched on 12 July 2000. Zvezda is at the rear of the station according to its normal direction of travel and orientation, its engines are used to boost the station's orbit. Alternatively Russian and European spacecraft can dock to Zvezda's aft (rear) port and use their engines to boost the station.

Destiny is the primary research facility for United States payloads aboard the ISS. In 2011, NASA solicited proposals for a not-for-profit group to manage all American science on the station which does not relate to manned exploration. The module houses 24 International Standard Payload Racks, some of which are used for environmental systems and crew daily living equipment. Destiny also serves as the mounting point for the station's Truss Structure.

Quest is the only USOS airlock, Quest hosts spacewalks with both United States EMU
Extravehicular Mobility Unit
The Space Shuttle/International Space Station Extravehicular Mobility Unit is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Space Shuttle or International Space Station crew member to perform extra-vehicular activity...

 and Russian Orlan spacesuits
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

. Quest consists of two segments; the equipment lock, that stores spacesuits and equipment, and the crew lock, from which astronauts can exit into space. This module has a separately controlled atmosphere. Crew sleep in this module, breathing a low nitrogen mixture the night before scheduled EVAs, to avoid decompression sickness (known as "the bends") in the low pressure suits.
Pirs ' onMouseout='HidePop("39947")' href="/topics/Pier">pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...

"), , and Poisk , also known as the Mini-Research Module
Mini-Research Module
International Space Station modules* Mini-Research Module 1 * Mini-Research Module 2 Other research modules of the Russian Orbital Segment:* Multipurpose Laboratory Module * Russian Research Modules...

 2 (MRM 2), , or МИМ 2. Pirs and Poisk are Russian airlock modules. Each of these modules have 2 identical hatches. An outward opening hatch on the MIR space station failed after it swung open too fast after unlatching, due to a small amount of air pressure remaining in the airlock. A different entry was used, and the hatch repaired. All EVA hatches on the ISS open inwards and are pressure sealing. Pirs is used to store, service, and refurbish Russian Orlan suits and provides contingency entry for crew using the slightly bulkier American suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.

Harmony, is the second of the station's node modules and the utility hub of the USOS. The module contains four racks that provide electrical power, bus electronic data, and acts as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The European Columbus and Japanese Kibō laboratories are permanently berthed to two of the radial ports, the other two can used for the HTV. American Shuttle Orbiters docked with the ISS via PMA-2, attached to the forward port. Tranquility is the third and last of the station's U.S. nodes, it contains an additional life support system to recycle waste water for crew use and supplements oxygen generation. Three of the four berthing locations are not used, one has the cupola installed and one has the docking port adapter installed.

Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

, the primary research facility for European payloads aboard the ISS, provides a generic laboratory
European Drawer Rack
The European Drawer Rack is a single, six-post International Standard Payload Rack with seven Experiment Modules , each of which has separate access to power and cooling. A Video Management Unit sends streaming video, images, and science data to Earth via the Columbus module's high-rate data...

 as well as facilities specifically designed for biology
Biolab
Biolab is a single-rack multi-user science payload designed for use in the Columbus laboratory of the International Space Station.Biolab does support biological research on small plants, small invertebrates, microorganisms, animal cells, and tissue cultures.It includes an incubator equipped with...

, biomedical research
European Physiology Modules
The European Physiology Module is an International Standard Payload Rack for the Columbus Laboratory on board the International Space Station. The EPM rack was built by OHB-System in Bremen....

 and fluid physics
Fluid Science Laboratory
The Fluid Science Laboratory is a European science payload designed for use in Columbus built by Alenia Aeronautica Spazio and OHB-System. It is a multi-user facility for conducting fluid physics research in microgravity conditions...

. Several mounting locations are affixed to the exterior of the module, which provide power and data to external experiments such as the European Technology Exposure Facility
European Technology Exposure Facility
The European Technology Exposure Facility is a payload mounted on the exterior of the European Columbus laboratory, one of the modules of the International Space Station...

 (EuTEF), Solar Monitoring Observatory
Solar Monitoring Observatory
The Solar Monitoring Observatory is an ESA science observatory that is part of the Columbus Laboratory, which is a component of the International Space Station. The Columbus module was launched February 2008 aboard STS-122. SOLAR was externally mounted to the Columbus Laboratory, together with...

, Materials International Space Station Experiment
Materials International Space Station Experiment
The Materials International Space Station Experiment , is a series of experiments mounted externally on the International Space Station that investigates the effects of long-term exposure of materials to the harsh space environment....

, and Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space is a project led by the European Space Agency which will place an ultra-stable atomic clock on the International Space Station...

. A number of expansions are planned for the module to study quantum physics and cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

.
Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 ' onMouseout='HidePop("4400")' href="/topics/Hope">hope
Hope
Hope is the emotional state which promotes the belief in a positive outcome related to events and circumstances in one's life. It is the "feeling that what is wanted can be had or that events will turn out for the best" or the act of "look[ing] forward to with desire and reasonable confidence" or...

") is the largest single ISS module. This laboratory is used to carry out research in space medicine, biology, Earth observations, materials production, biotechnology, communications research, and has facilities for growing plants and fish. The laboratory contains a total of 23 racks, including 10 experiment racks and has a dedicated airlock for experiments. In a 'shirt sleeves' environment, crew attach an experiment to the sliding drawer within the airlock, close the inner, and then open the outer hatch. By extending the drawer and removing the experiment using the dedicated robotic arm, payloads are placed on the external platform. The process can be reversed and repeated quickly, allowing access to maintain external experiments without the delays caused by EVA's. Only the Russian and Japanese laboratories have this feature. A smaller pressurized module is attached to the top of Kibō, serving as a cargo bay. The dedicated Interorbital communications system allows large amounts of data to be beamed from Kibō's ICS, first to the Japanese KODAMA satellite in geostationary orbit, then to Japanese ground stations. When a direct communication link is used, contact time between the ISS and a ground station is limited to approximately 10 minutes per visible pass. When KODAMA relays data between a LEO spacecraft and a ground station, real-time communications are possible in 60% of the flight path of the spacecraft. Ground staff use tele-present robotics to conduct on-orbit research without crew intervention.

Cupola is an observatory, its seven windows are used to conduct experiments, observations of Earth and docking spacecraft. The Cupola project was started by NASA and Boeing, but canceled due to budget cuts. A barter agreement between NASA and the ESA resulted in the Cupola's development being resumed in 1998 by the ESA. The module comes equipped with robotic workstations for operating the station's main robotic arm and shutters to protect its windows from damage caused by micrometeorites. It features a 80 centimetres (31.5 in) round window, the largest window on the station.
Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

 , also known as the Mini-Research Module 1 (MRM-1) and formerly known as the Docking Cargo Module (DCM), is similar in design to the Mir Docking Module
Mir Docking Module
The Stykovochnyy Otsek , GRAU index 316GK, otherwise known as the Mir docking module or SO, was the sixth module of the Russian space station Mir, launched in November 1995 aboard the...

 launched on STS-74
STS-74
STS-74 was a Space Shuttle Atlantis mission to the Mir space station. It was the fourth mission of the US/Russian Shuttle-Mir Program, and it carried out the second docking of a space shuttle to Mir. Atlantis lifted off for the mission on 12 November 1995 from Kennedy Space Center launch pad 39A,...

 in 1995. Rassvet is primarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISS aboard NASA's on the STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

 mission and connected in May 2010, Rassvet is the only Russian owned module launched by NASA, to repay for the launch of Zarya, which is Russian designed and built, but partially paid for by NASA. Rassvet was launched with the Russian Nauka Laboratory's Experiments airlock temporarily attached to it, and spare parts for the European Robotic Arm.

Leonardo PPM The three NASA Space shuttle MPLM
Multi-Purpose Logistics Module
A Multi-Purpose Logistics Module is a large pressurized container used on Space Shuttle missions to transfer cargo to and from the International Space Station . An MPLM was carried in the cargo bay of a Shuttle and berthed to the Unity or Harmony modules on the ISS. From there, supplies were...

 cargo containers Leonardo, Raffaello and Donatello, were built for NASA in Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 by Alcatel Alenia Space, now Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...

. The MPLMs are provided to the ISS programme by the Italy (independent of Italy's role as a member state of ESA) to NASA and are considered to be U.S. elements. In a bartered exchange for providing these containers, the U.S. has given Italy research time aboard the ISS out of the U.S. allotment in addition to that which Italy receives as a member of ESA. The Permanent Multipurpose Module was created by converting Leonardo into a module that could be permanently attached to the station.

Scheduled additional modules

Nauka , also known as the Multipurpose Laboratory Module (MLM) or FGB-2, (Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

: Многофункциональный лабораторный модуль, or МЛМ), is the major Russian laboratory module. This module will be separated from the ISS before de-orbit with support modules and become the OPSEK space station, it contains an additional set of life support systems and orientation control, and power provided by its solar arrays will mean the ROS no longer relies on power from the USOS main arrays. Nauka's mission has changed over time, during the mid 1990's it was intended as a backup for the FGB, and later as a universal docking module (UDM), its docking ports will be able to support automatic docking of both space craft, additional modules and fuel transfer. Prior to the arrival of the MLM, a progress robot spacecraft will dock with PIRS, depart with that module, and both will be discarded. Nauka will then use its own engines to attach itself to the ROS in 2012.

Node Module
Node Module
The Node Module is a pressurized module of the Russian Segment of the International Space Station and will be used in the OPSEK space station...

 (UM)/(NM) This 4-ton ball shaped module will support the docking of two scientific and power modules during the final stage of the station assembly and provide the Russian segment additional docking ports to receive Soyuz TMA (transportation modified anthropometric) and Progress M spacecraft. NM is to be incorporated into the ISS in 2012. It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion and flight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of the Nauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. However more importantly, the node module was conceived to serve as the only permanent element of the future Russian successor to the ISS, OPSEK. Equipped with six docking ports, the Node Module would serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. This would be a progression beyond the ISS and Russia's modular MIR space station, which are in turn more advanced than early monolithic first generation stations such as Skylab, and early Salyut and Almaz stations.

Science Power Modules 1 & 2 (NEM-1, NEM-2)

Cancelled components

The International Space Station (ISS) is a habitable, artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 in low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

. The ISS follows the Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

, Almaz
Almaz
The Almaz program was a series of military space stations launched by the Soviet Union under cover of the civilian Salyut DOS-17K program after 1971....

, Cosmos
Cosmos 557
Kosmos 557 was the designation given to DOS-3, the next space station in the Salyut program. It was originally intended to be launched as Salyut-2, but due to its failure to achieve orbit on May 11, 1973, three days before the launch of Skylab, it was renamed Kosmos-557.Due to errors in the flight...

, Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, and Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space stations, as the 11th space station launched, not including the Genesis
Genesis II
Genesis II is a 1973 American TV film created and produced by Gene Roddenberry and directed by John Llewellyn Moxey.It opens with the line, "My name is Dylan Hunt...

 I and II prototypes. The ISS serves as a research laboratory that has a microgravity environment in which crews conduct experiments in many fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, human biology
Human biology
Human Biology is an interdisciplinary area of study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, epidemiology, ecology, nutrition, population genetics and sociocultural influences. It is closely related to...

, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. The station has a unique environment for the testing of the spacecraft systems that will be required for missions to the Moon and Mars. The station is expected to remain in operation until at least 2020, and potentially to 2028. Russia's next planned space station OPSEK
Orbital Piloted Assembly and Experiment Complex
The Orbital Piloted Assembly and Experiment Complex ' is the planned Russian successor to the International Space Station, with the main goal of supporting deep space exploration.-Overview:...

, is to be separated prior to the ISS's deorbit to form a new, separate space station, intended to support deep space exploration. Like many artificial satellites, the ISS can be seen from Earth with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...

. The ISS is operated by Expedition crews, and has been continuously staffed since 2 November 2000—an uninterrupted human presence in space for the past . , the crew of Expedition 29
Expedition 29
Expedition 29 was the 29th long-duration expedition to the International Space Station . The expedition formally began with the departure from the ISS of the Soyuz TMA-21 spacecraft at 00:38 UTC on on 16 September 2011...

 is aboard.

The ISS combines the Japanese Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 laboratory with three space station projects, the Soviet/Russian Mir-2
Mir-2
Mir-2 was a space station project begun in February 1976. Some of the modules built for Mir-2 have been incorporated into the International Space Station . The project underwent many changes, but was always based on the DOS-8 base block space station core module, built as a back-up to the DOS-7...

, the American Freedom
Space Station Freedom
Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after...

, and the European Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

. Budget constraints led to the merger of these projects into a single multi-national programme. The ISS is a third generation modular space station, comparable to MIR, OPSEK and Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

, consisting of pressurised modules, external trusses, solar arrays and other components which have been launched by Russian Proton rockets, American space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

s, and Russian Soyuz rockets. The station is maintained in orbit between 278 km (173 mi) and 460 km (286 mi) altitude, and travels at an average ground speed
Ground speed
Ground speed is the speed of an aircraft relative to the ground. Information displayed to passengers through the entertainment system often gives the aircraft groundspeed rather than airspeed....

 of 27,724 km (17,227 mi) per hour, completing 15.7 orbits per day.

The ISS is a joint project between the five participating space agencies, the American NASA, the Russian RKA
Russian Federal Space Agency
The Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...

, the Japanese JAXA
Japan Aerospace Exploration Agency
The , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...

, the European ESA
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

, and the Canadian CSA. The ownership and use of the space station is established in intergovernmental treaties and agreements which divide the station into two areas and allow the Russian Federation to retain full ownership of Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS)/(RS), with the US Orbital Segment
US Orbital Segment
The US Orbital Segment is the name given to the components of the International Space Station constructed and operated by the US National Aeronautics and Space Administration , European Space Agency , Canadian Space Agency and Japan Aerospace Exploration Agency .The segment currently consists of...

 (USOS) allocated between the other international partners. The station is serviced by Soyuz spacecraft, Progress spacecraft, the Automated Transfer Vehicle
Automated Transfer Vehicle
The Automated Transfer Vehicle or ATV is an expendable, unmanned resupply spacecraft developed by the European Space Agency . ATVs are designed to supply the International Space Station with propellant, water, air, payload and experiments...

 and the H-II Transfer Vehicle
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

, and has been visited by astronauts and cosmonauts from 15 different nations.

Purpose

According to the original Memorandum of Understanding between NASA and RSA, the International Space Station was intended to be a laboratory, observatory and factory in space. It was also planned to provide transportation, provide servicing and act as a staging base for possible future missions to the Moon, Mars and asteroids. In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic, and educational purposes.

Scientific research

The ISS provides a platform to conduct scientific research that cannot be performed in any other way. While unmanned spacecraft can provide platforms for zero gravity and exposure to space, the ISS offers a long term environment where studies can be performed potentially for decades, combined with ready access by human researchers over periods that exceed the capabilities of manned spacecraft. Kibō is intended to accelerate Japan's progress in science and technology, gain new knowledge and apply it to such fields as industry and medicine. The Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 (AMS), which NASA compares to the Hubble telescope, could not be accommodated on a free flying satellite platform, due in part to its power requirements and data bandwidth needs. The Station simplifies individual experiments by eliminating the need for separate rocket launches and research staff.
The primary fields of research include Space weather
Space weather
Space weather is the concept of changing environmental conditions in near-Earth space or thespace from the Sun's atmosphere to the Earth's atmosphere. It is distinct from the concept ofweather within the Earth's planetary atmosphere...

, human research, space medicine
Space medicine
Space medicine is the practice of medicine on astronauts in outer space whereas astronautical hygiene is the application of science and technology to the prevention or control of exposure to the hazards that may cause astronaut ill health. Both these sciences work together to ensure that...

, life sciences, physical science
Physical science
Physical science is an encompassing term for the branches of natural science and science that study non-living systems, in contrast to the life sciences...

s, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. Scientists on Earth have access to the crew's data and can modify experiments or launch new ones; benefits generally unavailable on unmanned spacecraft. Crews fly expeditions of several months duration, providing approximately 160 man-hours a week of labor with a crew of 6.

Research on the ISS improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy
Muscle atrophy
Muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass...

, bone loss
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...

, and fluid shift. This data will be used to determine whether lengthy human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....

 and space colonization
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...

 are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars
Manned mission to Mars
A manned mission to Mars has been the subject of science fiction, engineering, and scientific proposals throughout the 20th century and into the 21st century...

.
Medical studies are conducted aboard the ISS on behalf of the National Space and Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity
Advanced Diagnostic Ultrasound in Microgravity
The Advanced Diagnostic Ultrasound in Microgravity Project is a US Government funded study investigating strategies for applying diagnostic telemedicine to space. The Principal Investigator is Scott Dulchavsky, Chairman of Surgery at the Henry Ford Health System...

 study in which astronauts perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.

Microgravity

Gravity is the only significant force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

 acting upon the ISS, which is in constant freefall
Free fall
Free fall is any motion of a body where gravity is the only force acting upon it, at least initially. These conditions produce an inertial trajectory so long as gravity remains the only force. Since this definition does not specify velocity, it also applies to objects initially moving upward...

. This state of freefall, or perceived weightlessness, is not perfect however, being disturbed by four separate effects: One, the drag resulting from the residual atmosphere, when the ISS enters the Earth's shadow, the main solar panels are rotated to minimize this aerodynamic drag, helping reduce orbital decay
Orbital decay
Orbital decay is the process of prolonged reduction in the altitude of a satellite's orbit.This can be due to drag produced by an atmosphere due to frequent collisions between the satellite and surrounding air molecules. The drag experienced by the object is larger in the case of increased solar...

. Two, vibration caused by mechanical systems and the crew on board the ISS. Three, orbital corrections by the on-board gyroscopes or thrusters. Four, the spatial separation from the real centre of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

 of the ISS. Any part of the ISS not at the exact center of mass will tend to follow its own orbit
Gravity-gradient stabilization
Gravity-gradient stabilization is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and the Earth's gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction...

. That is, parts on the underside, closer to the Earth are pulled harder, towards the Earth. Conversely, parts on the top of the station, further from Earth, try to fling off into space. However, as each point is physically part of the station, this is impossible, and so each component is subject to small forces which keep them attached to the station as it orbits. This is also called the tidal force
Tidal force
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...

.

Researchers are investigating the effect of the station's near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate microgravity's effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.

The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour of fluids better. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding of superconductivity
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

.

The study of materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...

 is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

s, ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, water vapour
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

, and oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

s in Earth's atmosphere, as well as cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s, cosmic dust
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...

, antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

, and dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 in the universe.

Exploration

The ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will be required for long-duration missions to the Moon and Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

. This provides experience in the maintenance, repair, and replacement of systems on-orbit, which will be essential in operating spacecraft farther from Earth. Mission risks are reduced, and the capabilities of interplanetary spacecraft are advanced. The ESA states that "Whereas the ISS is essential for answering questions concerning the possible impact of weightlessness, radiation and other space-specific factors, other aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations".

A Mars exploration mission may be a multinational effort involving space agencies and countries outside the current ISS partnership. In 2010 ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other 4 partners that China, India and South Korea be invited to join the ISS partnership. NASA chief Charlie Bolden stated in Feb 2011 "Any mission to Mars is likely to be a global effort". As of 2011, the space agencies of Europe, Russia and China carried out the ground-based preparations in the Mars500 project, which complement the ISS-based preparations for a manned mission to Mars. China launched its own space station in September 2011, and has officially initiated its programme for a modular station. However, China has indicated a willingness to cooperate further with other countries on manned exploration.

Education and cultural outreach

The ISS crew provide opportunities for students on Earth by running student-developed experiments, making educational demonstrations, allowing for student participation in classroom versions of ISS experiments, and directly engaging students using radio, videolink and email. Cultural activities are another major objective. There is something about space that touches even people who are not interested in science.

Amateur Radio on the ISS (ARISS) is a volunteer programme which inspires students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

 communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from 9 countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.

JAXA aims both to 'Stimulate the curiosity of children, cultivating their spirits, and encouraging their passion to pursue craftsmanship', and to 'Heighten the child's awareness of the importance of life and their responsibilities in society.' Through a series of education guides, a deeper understanding of the past and near-term future of manned space flight, as well as that of Earth and life, will be learned. In the JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISS is explored. Students grow sunflower seeds which flew on the ISS for about nine months as a start to ‘touch the Universe’. In the first phase of kibo utilization from 2008 to mid-2010, researchers from more than a dozen Japanese universities conducted experiments in diverse fields.

ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms. In one lesson, students can navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.

First Orbit
First Orbit
First Orbit is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker...

 is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker Christopher Riley and ESA astronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital space flight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced from the Russian State Archive. Nespoli, during Expedition 26/27, filmed the majority of the footage for this documentary film, and as a result is credited as its director of photography
Cinematographer
A cinematographer is one photographing with a motion picture camera . The title is generally equivalent to director of photography , used to designate a chief over the camera and lighting crews working on a film, responsible for achieving artistic and technical decisions related to the image...

. The film was streamed through the website www.firstorbit.org in a global YouTube
YouTube
YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....

 premiere in 2011, under a free license.

Origins

The International Space Station represents a combination of three national space station projects, NASA's Freedom, the RSA's Mir-2, and the European Columbus space stations. In September 1993, American Vice-President Al Gore, Jr., and Russian Prime Minister Viktor Chernomyrdin
Viktor Chernomyrdin
Viktor Stepanovich Chernomyrdin was the founder and the first chairman of the Gazprom energy company, the longest serving Prime Minister of Russia and Acting President of Russia for a day in 1996. He was a key figure in Russian politics in the 1990s, and a great contributor to the Russian...

 announced plans for a new space station, which eventually became the International Space Station. They also agreed, in preparation for this new project, that the United States would be involved in the Mir programme, including American Shuttles docking, in the Shuttle-Mir Program
Shuttle-Mir Program
The Shuttle–Mir Program was a collaborative space program between Russia and the United States, which involved American Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the shuttle and an American astronaut flying aboard a Soyuz spacecraft to engage in...

. According to the plan, the International Space Station programme would combine the proposed space stations of all participant agencies and the Japanese Kibō laboratory.

NASA's Freedom

In the early 1980s, NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 planned to launch a modular space station called Freedom as a counterpart to the Soviet Salyut and Mir space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...

s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, "We can follow our dreams to distant stars, living and working in space for peaceful economic and scientific gain", Freedom was never constructed or completed as originally designed, and after several cutbacks, the remnants of the project became part of the ISS. Several NASA Space Shuttle missions in the 1980s and early 1990s included spacewalks to demonstrate and test space station construction techniques.

NASA's first cost assessment in 1987 revealed the 'Dual Keel' Station would cost $14.5 billion. This caused a political uproar in Congress, and NASA and Reagan Administration officials reached a compromise in March 1987 which allowed the agency to proceed with a cheaper $12.2-billion Phase One Station that could be completed after 10 or 11 Shuttle assembly flights. This design initially omitted the $3.4-billion 'Dual Keel' structure and half of the power generators. The new Space Station configuration was named 'Freedom' by Reagan in June 1988. Originally, Freedom would have carried two 37.5 kW solar arrays. However, Congress quickly insisted on adding two more arrays for scientific users. The Space Station programme was plagued by conflicts during the entire 1984-87 definition phase. In 1987, the Department of Defense (DoD) briefly demanded to have full access to the Station for military research, despite strong objections from NASA and the international partners. Besides the expected furor from the international partners, the DoD position sparked a shouting match between Defense Secretary Caspar Weinberger and powerful members of Congress that extended right up to the final Fiscal 1988 budget authorization in July 1987. Reagan wanted to invite other NATO countries to participate in the U.S-led project, since the Soviet Union had been launching international crews to their Salyut space stations since 1971. At one point, then-anonymous disgruntled NASA employees calling themselves "Center for Strategic Space Studies" suggested that instead of building Freedom, NASA should take the back-up Skylab from display in the National Air and Space Museum in Washington and launch that.

The space station was also going to tie the emerging European and Japanese national space programmes closer to the U.S.-led project, thereby preventing those nations from becoming major, independent competitors too. An agreement signed in September 1988 allocated 97% of the US lab resources to NASA while the Canadian CSA would receive 3% in return for its contribution to the programme. Europe and Japan would retain 51% of their own laboratory modules. Six Americans and two international astronauts would be permanently based on Space Station Freedom.

Russia's Mir-2



The Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS or RS) is the eleventh Soviet-Russian space station. Mir and the ISS are successors to the Salyut and Almaz stations. Mir-2 was originally authorized in the February 1976 resolution setting forth plans for development of third generation Soviet space systems. The first MIR-2 module was launched in 1986 by an Energia
Energia
Energia was a Soviet rocket that was designed by NPO Energia to serve as a heavy-lift expendable launch system as well as a booster for the Buran spacecraft. Control system main developer enterprise was the NPO "Electropribor"...

 heavy-lift expendable launch system. The launcher worked properly, however the Polyus payload fired its engines to insert itself into orbit whilst in the wrong position due to a programming error, and re-entered the atmosphere. The planned station changed several times, but Zvezda was always the service module. The station would have used the Buran
Buran
Buran may refer to:* Buran , a Soviet space shuttle** Buran program, which developed the spacecraft* Buran eavesdropping device, invented by Léon Theremin, used by soviet intelligence* Buran cruise missile, a Soviet cruise missile...

 space shuttle and Proton rockets to lift new modules into orbit. The spaceframe of Zvezda, also called DOS-8 serial number 128, was completed in February 1985 and major internal equipment was installed by October 1986.

The Polyus module or spacecraft, which would have served the same function as Zarya, looked like a "Salyut" slightly modified for this task and was made up from parts of the ships "Cosmos-929, -1267, -1443, -1668" and from modules of MIR-2 station. There are two different descriptions of the weapon systems. In one, Polyus is described as a space-borne nuclear bomber, in another it is described as a satellite interceptor, carrying a 1 MegaWatt carbon dioxide laser. The module had a length of almost 37 m and a diameter of 4.1 m weighed nearly 80 t and included 2 principal sections, the smallest, the functional service block (FGB) and the largest, the aim module.

In 1983, the design was changed and the station would consist of Zvezda, followed by several 90 metric ton modules and a truss structure similar to the current station. The draft was approved by NPO Energia Chief Semenov on 14 December 1987 and announced to the press as 'Mir-2' in January 1988. This station would be visited by the Russian Space Shuttle Buran, but mainly resupplied by Progress-M2 spacecraft. Orbital assembly of the station was expected to begin in 1993. In 1993 with the collapse of the Soviet Union, a redesigned smaller Mir-2 was to be built whilst attached to Mir, just as OPSEK is being assembled whilst attached to the ISS.

Japan's Kibō

Conceived in 1985, the Japanese Experiment Module (JEM) or Kibō consists of a pressurized laboratory mainly dedicated to advanced technology experiments, a logistics module, an unpressurized pallet for vacuum experiments in space plus a robotic arm. While the proposed space station was redesigned many times around Kibō, the only significant change has been additional ballistic shielding, as its final position at the front of the station increases the risk of damage from debris. The Japanese National Space Development Agency (NASDA) formally submitted the JEM proposal to NASA in March 1986.

In 1986 the Japanese contribution was estimated to be worth $1.9-3.2 billion for a JEM launch in 1995. By 1990, the schedule had slipped by three years due to NASA budget cuts and space station cost overruns. The delays increased the JEM's total cost slightly, from $2.3 billion in 1986 to $2.63 billion in 1993, when the launch was postponed to 1999. Final hardware production began in the mid-1990s and the Japanese robotic arm was tested on a NASA Space Shuttle flight in August 1997. According to plans prior to the Columbia disaster, the JEM would be launched in 2002-03.


In 2010, Kibō won the Good Design Award, a year old consumer and industry award which identifies the best of Japanese craftsmanship. During August 2011, an observatory mounted on Kibō, which utilizes the ISS's orbital motion to image the whole sky in the X-ray spectrum, detected for the first time the moment a star was swallowed by a black hole.

ESA's Columbus

The Columbus Man-Tended Free Flyer (MTFF) was a European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 (ESA) programme to develop a space station that could be used for a variety of microgravity experiments while serving ESA's needs for an autonomous manned space platform. The programme ran from 1986 to 1991, was expected to cost $3.56 billion including launch and utilization, and was cancelled while still in the planning stage. Aspects of the programme were later realised in the Columbus module.

In November 1992, further financial difficulties in Russia and uncertainties with America's Freedom space station led Russia and the European Space Agency to open discussions on joint development and use of Mir-2.

Station structure

The ISS is a 'third generation' or modular space station. Other examples of modular station projects include the Soviet/Russian MIR, Russian OPSEK, and Chinese Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

. The first space station, Salyut 1
Salyut 1
Salyut 1 was the first space station of any kind, launched by the USSR on April 19, 1971. It was launched unmanned using a Proton-K rocket. Its first crew came later in Soyuz 10, but was unable to dock completely; its second crew launched in Soyuz 11 and remained on board for 23 days...

, and other one-piece or 'monolithic' first generation space stations, such as Salyut 2,3,4,5, DOS 2, Kosmos 557, Almaz and NASA's Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

 stations were not designed for re-supply. Each crew had to depart the station to free the only docking port for the next crew to arrive. Second generation station projects such as Salyut 6 and 7 feature a second docking port. Third generation stations are modular stations, this allows the mission to be changed over time, new modules can be added or removed from the existing structure, saving considerable costs and allowing greater flexibility.

Below is a diagram of major station components. The blue areas are pressurized sections accessible by the crew without using spacesuits. The station's unpressurized superstructure is indicated in red. Other unpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.


Assembly


The assembly of the International Space Station, a major endeavour in space architecture
Space architecture
Space architecture, in its simplest definition, is the theory and practice of designing and building inhabited environments in outer space. The architectural approach to spacecraft design addresses the total built environment, drawing from diverse disciplines including physiology, psychology, and...

, began in November 1998. Russian modules launch and dock robotically, with the exception of Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

. All other modules were delivered by space shuttle, which required installation by ISS and shuttle crewmembers using the SSRMS and EVAs; , they had added 159 components during more than 1,000 hours of EVA activity. 127 of these spacewalks originated from the station, while the remaining 32 were launched from the airlocks of docked space shuttles. The beta angle
Beta angle
The beta angle is a value that is used most notably in spaceflight. The beta angle determines the percentage of time an object such as a spacecraft in low Earth orbit spends in direct sunlight, absorbing solar energy. Beta angle is defined as the angle between the orbit plane and the vector from...

 of the station had to be considered at all times during construction, as the station's beta angle is directly related to the percentage of its orbit that the station (as well as any docked or docking spacecraft) is exposed to the sun; the space shuttle would not perform optimally above a limit called the "beta cutoff". Rassvet was delivered by NASA's Atlantis Space Shuttle in 2010 in exchange for the Russian Proton delivery of the United States-funded Russian-built Zarya Module in 1998. Robot arms rather than EVAs were utilized in its installation (docking).

The first segment of the ISS, Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

, was launched on 20 November 1998 on an autonomous Russian Proton rocket. It provided propulsion, orientation control, communications, electrical power, but lacked long-term life support functions. Two weeks later a passive NASA module Unity was launched aboard Space Shuttle flight STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 and attached to Zarya by astronauts during EVAs. This module has two Pressurized Mating Adapter
Pressurized Mating Adapter
The International Space Station uses three Pressurized Mating Adapters to interconnect spacecraft and modules with different docking mechanisms. The first two PMAs were launched with the Unity module in 1998 aboard STS-88...

s (PMAs), one connects permanently to Zarya, the other allows the space shuttle to dock to the space station. At this time, the Russian station Mir was still inhabited. The ISS remained unmanned for two years, during which time Mir was de-orbited. On July 12, 2000 Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive vehicle for a rendezvous with the Zarya and Unity. As a passive "target" vehicle, the Zvezda maintained a stationkeeping orbit as the Zarya-Unity vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. Zarya's computer transferred control of the station to Zvezda's computer soon after docking. Zvezda added sleeping quarters, a toilet, kitchen, CO2 scrubbers, dehumidifier, oxygen generators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.

The first resident crew, Expedition 1
Expedition 1
Expedition 1, or Expedition One, was the first long-duration stay on the International Space Station . The three-person crew stayed aboard the station for 136 days, from November 2000 to March 2001. It was the beginning of an uninterrupted human presence on the station which still continues, as of...

, arrived in November 2000 on Soyuz TM-31
Soyuz TM-31
Soyuz TM-31 was the first Soyuz spacecraft to dock with the International Space Station . Launched near the end of 2000 the Soyuz-TM spacecraft brought to ISS Expedition 1, the first long-duration ISS crew...

, midway between the flights of STS-92
STS-92
STS-92 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Discovery. STS-92 marked the 100th mission of the Space Shuttle...

 and STS-97
STS-97
STS-97 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Endeavour. The crew installed the first set of solar arrays to the ISS, prepared a docking port for arrival of the Destiny Laboratory Module, and delivered supplies for the station's crew.-Crew:-Mission...

. These two Space Shuttle flights each added segments of the station's Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

, which provided the station with Ku-band communication for U.S. television, additional attitude support needed for the additional weight of the USOS, and substantial solar arrays supplementing the station's existing 4 solar arrays.

Over the next two years the station continued to expand. A Soyuz-U
Soyuz-U
The Soyuz-U launch vehicle is an improved version of the original Soyuz LV. Soyuz-U is part of the R-7 family of rockets based on the R-7 Semyorka missile. Members of this rocket family were designed by the TsSKB design bureau and constructed at the Progress Factory in Samara, Russia....

 rocket delivered the Pirs docking compartment. The Space Shuttles Discovery, Atlantis
Space Shuttle Atlantis
The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...

, and Endeavour delivered the Destiny laboratory and Quest airlock, in addition to the station's main robot arm, the Canadarm2, and several more segments of the Integrated Truss Structure.

The expansion schedule was interrupted by the destruction of the on STS-107
STS-107
-Mission parameters:*Mass:**Orbiter Liftoff: **Orbiter Landing: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 90.1 min- Insignia :...

 in 2003, with the resulting hiatus in the Space Shuttle program
Space Shuttle program
NASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...

me halting station assembly until the launch of Discovery on STS-114
STS-114
-Original crew:This mission was to carry the Expedition 7 crew to the ISS and bring home the Expedition 6 crew. The original crew was to be:-Mission highlights:...

 in 2005.

The official resumption of assembly was marked by the arrival of Atlantis, flying STS-115
STS-115
Note:The P3/P4 Truss segment and batteries were so heavy that the crew count was reduced from seven to six.-Crew notes:...

, which delivered the station's second set of solar arrays. Several more truss segments and a third set of arrays were delivered on STS-116
STS-116
-Crew notes:Originally this mission was to carry the Expedition 8 crew to the ISS. The original crew was to be:-Mission highlights:* The STS-116 mission delivered and attached the International Space Station's third port truss segment, the P5 truss....

, STS-117
STS-117
- Crew Notes :The initial crew manifest before the Columbia accident was:Astronaut Mark Polansky was originally slated to pilot this mission, but was moved to STS-116, which he commanded...

, and STS-118
STS-118
- Crew notes :Astronaut Clayton Anderson originally was slated to be launched to the ISS on this mission, but was moved to STS-117. His replacement was Alvin Drew....

. As a result of the major expansion of the station's power-generating capabilities, more pressurised modules could be accommodated, and the Harmony node and Columbus European laboratory were added. These were followed shortly after by the first two components of Kibō. In March 2009, STS-119
STS-119
-Crew notes:This mission was originally scheduled to bring the Expedition 9 crew to the ISS. This crew would have consisted of:-Mission parameters:* Mass:* Orbiter liftoff: * Orbiter landing: * Perigee: * Apogee:...

 completed the Integrated Truss Structure with the installation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009 on STS-127
STS-127
STS-127 was a NASA Space Shuttle mission to the International Space Station . It was the twenty-third flight of . The primary purpose of the STS-127 mission was to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility , and the Exposed Section of the...

, followed by the Russian Poisk module. The third node, Tranquility, was delivered in February 2010 during STS-130
STS-130
STS-130 was a NASA Space Shuttle mission to the International Space Station . 's primary payloads were the Tranquility module and the Cupola, a robotic control station with six windows around its sides and another in the center, providing a 360-degree view around the station...

 by the Space Shuttle Endeavour, alongside the Cupola, closely followed in May 2010 by the penultimate Russian module, Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

, delivered by Space Shuttle Atlantis on STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

. The last pressurised module of the USOS, Leonardo, was brought to the station by Discovery on her final flight, STS-133
STS-133
STS-133 was the 133rd mission in NASA's Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discoverys 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011...

, followed by the Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 on STS-134
STS-134
STS-134 was the penultimate mission of NASA's Space Shuttle program. The mission marked the 25th and final flight of . This flight delivered the Alpha Magnetic Spectrometer and an ExPRESS Logistics Carrier to the International Space Station. Mark Kelly served as the mission commander...

, delivered by Endeavour.

, the station consisted of fifteen pressurised modules and the Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

. Still to be launched are the Russian Multipurpose Laboratory Module Nauka and a number of external components, including the European Robotic Arm
European Robotic Arm
The European Robotic Arm is a robotic arm to be attached to the Russian Segment of the International Space Station. It will be the first robot arm able to work on the Russian space station segments, and will supplement the two Russian Strela cargo cranes that are already installed on the Pirs...

. Assembly is expected to be completed by 2012, by which point the station will have a mass in excess of 400 metric tons (440 short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s).

The gross mass of the station is not possible to calculate with precision. The total launch weight of the modules on orbit is 417289 kilogram (as of 03/09/2011). The weight of experiments, spare parts, personal effects, crew, foodstuff, clothing, propellants, water supplies, gas supplies, docked spacecraft, and other items add to the total mass of the station. Gas (Hydrogen) is constantly vented overboard by the Oxygen generators.

Pressurised modules

Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

 , also known as the Functional Cargo Block or FGB , was the first module of the station, launched on November 20, 1998 on a Russian Proton rocket from Baikonur Cosmodrome Site 81
Baikonur Cosmodrome Site 81
Site 81 at the Baikonur Cosmodrome is a launch site used, along with Site 200, by Proton rockets. It consists of two launch pads, areas 23 and 24. Area 24 is currently used for Proton-K and Proton-M launches, while Area 23 is currently inactive....

 in Kazakhstan to a 400 km (248.5 mi) high orbit. After parking in orbit, the Zarya Module provided orientation control, communications and electrical power for itself, and for the passive Node 1 (Unity) attached later, while the station awaited launch of the third component, a Russian-provided crew living quarters and early station core, the service module Zvezda. The Service Module enhanced or replaced many functions of Zarya. The FGB is a descendant of the TKS spacecraft
TKS spacecraft
TKS spacecraft was a Soviet spacecraft design in the late 1960s intended to supply the military Almaz space station. The spacecraft was designed for manned or autonomous cargo resupply use...

 designed for the Russian Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

 programme. 6,100 kg of propellant fuel can be stored and transferred automatically to and from ships docked to the Russian portion of the station – the Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS). Zarya was originally intended as a module for the Russian Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space station, but was not flown as of the end of the Mir-1 programme. Development costs for Zarya were paid for by Russia (and the former Soviet Union), spread across previous space station programmes, and some construction and preparation costs were paid for by the United States. Unity, a passive connecting module was the first U.S.-built component of the Station. It is cylindrical in shape, with six berthing locations facilitating connections to other modules. Unity was carried into orbit as the primary cargo of STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 in 1998.

Zvezda , DOS-8, also known as the Service Module or SM . It provides all of the station's critical systems, its addition rendered the station permanently habitable for the first time, adding life support for up to six crew and living quarters for two. Zvezda's DMS-R computer handles guidance, navigation & control for the entire space station. A second computer which performs the same functions is installed in the Nauka FGB-2. The rocket used for Zvezda's launch was one of the first to carry advertising
Space advertising
Space advertising is the use of advertising in outer space or related to space flight. While there have only been a few examples of successful marketing campaigns, there have been several proposals to advertise in space, some even planning to launch giant billboards visible from the Earth...

. The space frame was completed in February 1985, major internal equipment was installed by October 1986, and it was launched on 12 July 2000. Zvezda is at the rear of the station according to its normal direction of travel and orientation, its engines are used to boost the station's orbit. Alternatively Russian and European spacecraft can dock to Zvezda's aft (rear) port and use their engines to boost the station.

Destiny is the primary research facility for United States payloads aboard the ISS. In 2011, NASA solicited proposals for a not-for-profit group to manage all American science on the station which does not relate to manned exploration. The module houses 24 International Standard Payload Racks, some of which are used for environmental systems and crew daily living equipment. Destiny also serves as the mounting point for the station's Truss Structure.

Quest is the only USOS airlock, Quest hosts spacewalks with both United States EMU
Extravehicular Mobility Unit
The Space Shuttle/International Space Station Extravehicular Mobility Unit is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Space Shuttle or International Space Station crew member to perform extra-vehicular activity...

 and Russian Orlan spacesuits
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

. Quest consists of two segments; the equipment lock, that stores spacesuits and equipment, and the crew lock, from which astronauts can exit into space. This module has a separately controlled atmosphere. Crew sleep in this module, breathing a low nitrogen mixture the night before scheduled EVAs, to avoid decompression sickness (known as "the bends") in the low pressure suits.
Pirs ' onMouseout='HidePop("66162")' href="/topics/Pier">pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...

"), , and Poisk , also known as the Mini-Research Module
Mini-Research Module
International Space Station modules* Mini-Research Module 1 * Mini-Research Module 2 Other research modules of the Russian Orbital Segment:* Multipurpose Laboratory Module * Russian Research Modules...

 2 (MRM 2), , or МИМ 2. Pirs and Poisk are Russian airlock modules. Each of these modules have 2 identical hatches. An outward opening hatch on the MIR space station failed after it swung open too fast after unlatching, due to a small amount of air pressure remaining in the airlock. A different entry was used, and the hatch repaired. All EVA hatches on the ISS open inwards and are pressure sealing. Pirs is used to store, service, and refurbish Russian Orlan suits and provides contingency entry for crew using the slightly bulkier American suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.

Harmony, is the second of the station's node modules and the utility hub of the USOS. The module contains four racks that provide electrical power, bus electronic data, and acts as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The European Columbus and Japanese Kibō laboratories are permanently berthed to two of the radial ports, the other two can used for the HTV. American Shuttle Orbiters docked with the ISS via PMA-2, attached to the forward port. Tranquility is the third and last of the station's U.S. nodes, it contains an additional life support system to recycle waste water for crew use and supplements oxygen generation. Three of the four berthing locations are not used, one has the cupola installed and one has the docking port adapter installed.

Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

, the primary research facility for European payloads aboard the ISS, provides a generic laboratory
European Drawer Rack
The European Drawer Rack is a single, six-post International Standard Payload Rack with seven Experiment Modules , each of which has separate access to power and cooling. A Video Management Unit sends streaming video, images, and science data to Earth via the Columbus module's high-rate data...

 as well as facilities specifically designed for biology
Biolab
Biolab is a single-rack multi-user science payload designed for use in the Columbus laboratory of the International Space Station.Biolab does support biological research on small plants, small invertebrates, microorganisms, animal cells, and tissue cultures.It includes an incubator equipped with...

, biomedical research
European Physiology Modules
The European Physiology Module is an International Standard Payload Rack for the Columbus Laboratory on board the International Space Station. The EPM rack was built by OHB-System in Bremen....

 and fluid physics
Fluid Science Laboratory
The Fluid Science Laboratory is a European science payload designed for use in Columbus built by Alenia Aeronautica Spazio and OHB-System. It is a multi-user facility for conducting fluid physics research in microgravity conditions...

. Several mounting locations are affixed to the exterior of the module, which provide power and data to external experiments such as the European Technology Exposure Facility
European Technology Exposure Facility
The European Technology Exposure Facility is a payload mounted on the exterior of the European Columbus laboratory, one of the modules of the International Space Station...

 (EuTEF), Solar Monitoring Observatory
Solar Monitoring Observatory
The Solar Monitoring Observatory is an ESA science observatory that is part of the Columbus Laboratory, which is a component of the International Space Station. The Columbus module was launched February 2008 aboard STS-122. SOLAR was externally mounted to the Columbus Laboratory, together with...

, Materials International Space Station Experiment
Materials International Space Station Experiment
The Materials International Space Station Experiment , is a series of experiments mounted externally on the International Space Station that investigates the effects of long-term exposure of materials to the harsh space environment....

, and Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space is a project led by the European Space Agency which will place an ultra-stable atomic clock on the International Space Station...

. A number of expansions are planned for the module to study quantum physics and cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

.
Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 ' onMouseout='HidePop("77473")' href="/topics/Hope">hope
Hope
Hope is the emotional state which promotes the belief in a positive outcome related to events and circumstances in one's life. It is the "feeling that what is wanted can be had or that events will turn out for the best" or the act of "look[ing] forward to with desire and reasonable confidence" or...

") is the largest single ISS module. This laboratory is used to carry out research in space medicine, biology, Earth observations, materials production, biotechnology, communications research, and has facilities for growing plants and fish. The laboratory contains a total of 23 racks, including 10 experiment racks and has a dedicated airlock for experiments. In a 'shirt sleeves' environment, crew attach an experiment to the sliding drawer within the airlock, close the inner, and then open the outer hatch. By extending the drawer and removing the experiment using the dedicated robotic arm, payloads are placed on the external platform. The process can be reversed and repeated quickly, allowing access to maintain external experiments without the delays caused by EVA's. Only the Russian and Japanese laboratories have this feature. A smaller pressurized module is attached to the top of Kibō, serving as a cargo bay. The dedicated Interorbital communications system allows large amounts of data to be beamed from Kibō's ICS, first to the Japanese KODAMA satellite in geostationary orbit, then to Japanese ground stations. When a direct communication link is used, contact time between the ISS and a ground station is limited to approximately 10 minutes per visible pass. When KODAMA relays data between a LEO spacecraft and a ground station, real-time communications are possible in 60% of the flight path of the spacecraft. Ground staff use tele-present robotics to conduct on-orbit research without crew intervention.

Cupola is an observatory, its seven windows are used to conduct experiments, observations of Earth and docking spacecraft. The Cupola project was started by NASA and Boeing, but canceled due to budget cuts. A barter agreement between NASA and the ESA resulted in the Cupola's development being resumed in 1998 by the ESA. The module comes equipped with robotic workstations for operating the station's main robotic arm and shutters to protect its windows from damage caused by micrometeorites. It features a 80 centimetres (31.5 in) round window, the largest window on the station.
Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

 , also known as the Mini-Research Module 1 (MRM-1) and formerly known as the Docking Cargo Module (DCM), is similar in design to the Mir Docking Module
Mir Docking Module
The Stykovochnyy Otsek , GRAU index 316GK, otherwise known as the Mir docking module or SO, was the sixth module of the Russian space station Mir, launched in November 1995 aboard the...

 launched on STS-74
STS-74
STS-74 was a Space Shuttle Atlantis mission to the Mir space station. It was the fourth mission of the US/Russian Shuttle-Mir Program, and it carried out the second docking of a space shuttle to Mir. Atlantis lifted off for the mission on 12 November 1995 from Kennedy Space Center launch pad 39A,...

 in 1995. Rassvet is primarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISS aboard NASA's on the STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

 mission and connected in May 2010, Rassvet is the only Russian owned module launched by NASA, to repay for the launch of Zarya, which is Russian designed and built, but partially paid for by NASA. Rassvet was launched with the Russian Nauka Laboratory's Experiments airlock temporarily attached to it, and spare parts for the European Robotic Arm.

Leonardo PPM The three NASA Space shuttle MPLM
Multi-Purpose Logistics Module
A Multi-Purpose Logistics Module is a large pressurized container used on Space Shuttle missions to transfer cargo to and from the International Space Station . An MPLM was carried in the cargo bay of a Shuttle and berthed to the Unity or Harmony modules on the ISS. From there, supplies were...

 cargo containers Leonardo, Raffaello and Donatello, were built for NASA in Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 by Alcatel Alenia Space, now Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...

. The MPLMs are provided to the ISS programme by the Italy (independent of Italy's role as a member state of ESA) to NASA and are considered to be U.S. elements. In a bartered exchange for providing these containers, the U.S. has given Italy research time aboard the ISS out of the U.S. allotment in addition to that which Italy receives as a member of ESA. The Permanent Multipurpose Module was created by converting Leonardo into a module that could be permanently attached to the station.

Scheduled additional modules

Nauka , also known as the Multipurpose Laboratory Module (MLM) or FGB-2, (Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

: Многофункциональный лабораторный модуль, or МЛМ), is the major Russian laboratory module. This module will be separated from the ISS before de-orbit with support modules and become the OPSEK space station, it contains an additional set of life support systems and orientation control, and power provided by its solar arrays will mean the ROS no longer relies on power from the USOS main arrays. Nauka's mission has changed over time, during the mid 1990's it was intended as a backup for the FGB, and later as a universal docking module (UDM), its docking ports will be able to support automatic docking of both space craft, additional modules and fuel transfer. Prior to the arrival of the MLM, a progress robot spacecraft will dock with PIRS, depart with that module, and both will be discarded. Nauka will then use its own engines to attach itself to the ROS in 2012.

Node Module
Node Module
The Node Module is a pressurized module of the Russian Segment of the International Space Station and will be used in the OPSEK space station...

 (UM)/(NM) This 4-ton ball shaped module will support the docking of two scientific and power modules during the final stage of the station assembly and provide the Russian segment additional docking ports to receive Soyuz TMA (transportation modified anthropometric) and Progress M spacecraft. NM is to be incorporated into the ISS in 2012. It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion and flight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of the Nauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. However more importantly, the node module was conceived to serve as the only permanent element of the future Russian successor to the ISS, OPSEK. Equipped with six docking ports, the Node Module would serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. This would be a progression beyond the ISS and Russia's modular MIR space station, which are in turn more advanced than early monolithic first generation stations such as Skylab, and early Salyut and Almaz stations.

Science Power Modules 1 & 2 (NEM-1, NEM-2)

Cancelled components

The International Space Station (ISS) is a habitable, artificial satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 in low Earth orbit
Low Earth orbit
A low Earth orbit is generally defined as an orbit within the locus extending from the Earth’s surface up to an altitude of 2,000 km...

. The ISS follows the Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

, Almaz
Almaz
The Almaz program was a series of military space stations launched by the Soviet Union under cover of the civilian Salyut DOS-17K program after 1971....

, Cosmos
Cosmos 557
Kosmos 557 was the designation given to DOS-3, the next space station in the Salyut program. It was originally intended to be launched as Salyut-2, but due to its failure to achieve orbit on May 11, 1973, three days before the launch of Skylab, it was renamed Kosmos-557.Due to errors in the flight...

, Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, and Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space stations, as the 11th space station launched, not including the Genesis
Genesis II
Genesis II is a 1973 American TV film created and produced by Gene Roddenberry and directed by John Llewellyn Moxey.It opens with the line, "My name is Dylan Hunt...

 I and II prototypes. The ISS serves as a research laboratory that has a microgravity environment in which crews conduct experiments in many fields including biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, human biology
Human biology
Human Biology is an interdisciplinary area of study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, epidemiology, ecology, nutrition, population genetics and sociocultural influences. It is closely related to...

, physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...

, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. The station has a unique environment for the testing of the spacecraft systems that will be required for missions to the Moon and Mars. The station is expected to remain in operation until at least 2020, and potentially to 2028. Russia's next planned space station OPSEK
Orbital Piloted Assembly and Experiment Complex
The Orbital Piloted Assembly and Experiment Complex ' is the planned Russian successor to the International Space Station, with the main goal of supporting deep space exploration.-Overview:...

, is to be separated prior to the ISS's deorbit to form a new, separate space station, intended to support deep space exploration. Like many artificial satellites, the ISS can be seen from Earth with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...

. The ISS is operated by Expedition crews, and has been continuously staffed since 2 November 2000—an uninterrupted human presence in space for the past . , the crew of Expedition 29
Expedition 29
Expedition 29 was the 29th long-duration expedition to the International Space Station . The expedition formally began with the departure from the ISS of the Soyuz TMA-21 spacecraft at 00:38 UTC on on 16 September 2011...

 is aboard.

The ISS combines the Japanese Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 laboratory with three space station projects, the Soviet/Russian Mir-2
Mir-2
Mir-2 was a space station project begun in February 1976. Some of the modules built for Mir-2 have been incorporated into the International Space Station . The project underwent many changes, but was always based on the DOS-8 base block space station core module, built as a back-up to the DOS-7...

, the American Freedom
Space Station Freedom
Space Station Freedom was a NASA project to construct a permanently manned Earth-orbiting space station in the 1980s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, Freedom was never constructed or completed as originally designed, and after...

, and the European Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

. Budget constraints led to the merger of these projects into a single multi-national programme. The ISS is a third generation modular space station, comparable to MIR, OPSEK and Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

, consisting of pressurised modules, external trusses, solar arrays and other components which have been launched by Russian Proton rockets, American space shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...

s, and Russian Soyuz rockets. The station is maintained in orbit between 278 km (173 mi) and 460 km (286 mi) altitude, and travels at an average ground speed
Ground speed
Ground speed is the speed of an aircraft relative to the ground. Information displayed to passengers through the entertainment system often gives the aircraft groundspeed rather than airspeed....

 of 27,724 km (17,227 mi) per hour, completing 15.7 orbits per day.

The ISS is a joint project between the five participating space agencies, the American NASA, the Russian RKA
Russian Federal Space Agency
The Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...

, the Japanese JAXA
Japan Aerospace Exploration Agency
The , or JAXA, is Japan's national aerospace agency. Through the merger of three previously independent organizations, JAXA was formed on October 1, 2003, as an Independent Administrative Institution administered by the Ministry of Education, Culture, Sports, Science and Technology and the...

, the European ESA
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

, and the Canadian CSA. The ownership and use of the space station is established in intergovernmental treaties and agreements which divide the station into two areas and allow the Russian Federation to retain full ownership of Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS)/(RS), with the US Orbital Segment
US Orbital Segment
The US Orbital Segment is the name given to the components of the International Space Station constructed and operated by the US National Aeronautics and Space Administration , European Space Agency , Canadian Space Agency and Japan Aerospace Exploration Agency .The segment currently consists of...

 (USOS) allocated between the other international partners. The station is serviced by Soyuz spacecraft, Progress spacecraft, the Automated Transfer Vehicle
Automated Transfer Vehicle
The Automated Transfer Vehicle or ATV is an expendable, unmanned resupply spacecraft developed by the European Space Agency . ATVs are designed to supply the International Space Station with propellant, water, air, payload and experiments...

 and the H-II Transfer Vehicle
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

, and has been visited by astronauts and cosmonauts from 15 different nations.

Purpose

According to the original Memorandum of Understanding between NASA and RSA, the International Space Station was intended to be a laboratory, observatory and factory in space. It was also planned to provide transportation, provide servicing and act as a staging base for possible future missions to the Moon, Mars and asteroids. In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic, and educational purposes.

Scientific research

The ISS provides a platform to conduct scientific research that cannot be performed in any other way. While unmanned spacecraft can provide platforms for zero gravity and exposure to space, the ISS offers a long term environment where studies can be performed potentially for decades, combined with ready access by human researchers over periods that exceed the capabilities of manned spacecraft. Kibō is intended to accelerate Japan's progress in science and technology, gain new knowledge and apply it to such fields as industry and medicine. The Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 (AMS), which NASA compares to the Hubble telescope, could not be accommodated on a free flying satellite platform, due in part to its power requirements and data bandwidth needs. The Station simplifies individual experiments by eliminating the need for separate rocket launches and research staff.
The primary fields of research include Space weather
Space weather
Space weather is the concept of changing environmental conditions in near-Earth space or thespace from the Sun's atmosphere to the Earth's atmosphere. It is distinct from the concept ofweather within the Earth's planetary atmosphere...

, human research, space medicine
Space medicine
Space medicine is the practice of medicine on astronauts in outer space whereas astronautical hygiene is the application of science and technology to the prevention or control of exposure to the hazards that may cause astronaut ill health. Both these sciences work together to ensure that...

, life sciences, physical science
Physical science
Physical science is an encompassing term for the branches of natural science and science that study non-living systems, in contrast to the life sciences...

s, astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...

 and meteorology
Meteorology
Meteorology is the interdisciplinary scientific study of the atmosphere. Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the 18th century. The 19th century saw breakthroughs occur after observing networks developed across several countries...

. Scientists on Earth have access to the crew's data and can modify experiments or launch new ones; benefits generally unavailable on unmanned spacecraft. Crews fly expeditions of several months duration, providing approximately 160 man-hours a week of labor with a crew of 6.

Research on the ISS improves knowledge about the effects of long-term space exposure on the human body, including muscle atrophy
Muscle atrophy
Muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass...

, bone loss
Osteoporosis
Osteoporosis is a disease of bones that leads to an increased risk of fracture. In osteoporosis the bone mineral density is reduced, bone microarchitecture is deteriorating, and the amount and variety of proteins in bone is altered...

, and fluid shift. This data will be used to determine whether lengthy human spaceflight
Human spaceflight
Human spaceflight is spaceflight with humans on the spacecraft. When a spacecraft is manned, it can be piloted directly, as opposed to machine or robotic space probes and remotely-controlled satellites....

 and space colonization
Space colonization
Space colonization is the concept of permanent human habitation outside of Earth. Although hypothetical at the present time, there are many proposals and speculations about the first space colony...

 are feasible. As of 2006, data on bone loss and muscular atrophy suggest that there would be a significant risk of fractures and movement problems if astronauts landed on a planet after a lengthy interplanetary cruise, such as the six-month interval required to travel to Mars
Manned mission to Mars
A manned mission to Mars has been the subject of science fiction, engineering, and scientific proposals throughout the 20th century and into the 21st century...

.
Medical studies are conducted aboard the ISS on behalf of the National Space and Biomedical Research Institute (NSBRI). Prominent among these is the Advanced Diagnostic Ultrasound in Microgravity
Advanced Diagnostic Ultrasound in Microgravity
The Advanced Diagnostic Ultrasound in Microgravity Project is a US Government funded study investigating strategies for applying diagnostic telemedicine to space. The Principal Investigator is Scott Dulchavsky, Chairman of Surgery at the Henry Ford Health System...

 study in which astronauts perform ultrasound scans under the guidance of remote experts. The study considers the diagnosis and treatment of medical conditions in space. Usually, there is no physician on board the ISS and diagnosis of medical conditions is a challenge. It is anticipated that remotely guided ultrasound scans will have application on Earth in emergency and rural care situations where access to a trained physician is difficult.

Microgravity

Gravity is the only significant force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...

 acting upon the ISS, which is in constant freefall
Free fall
Free fall is any motion of a body where gravity is the only force acting upon it, at least initially. These conditions produce an inertial trajectory so long as gravity remains the only force. Since this definition does not specify velocity, it also applies to objects initially moving upward...

. This state of freefall, or perceived weightlessness, is not perfect however, being disturbed by four separate effects: One, the drag resulting from the residual atmosphere, when the ISS enters the Earth's shadow, the main solar panels are rotated to minimize this aerodynamic drag, helping reduce orbital decay
Orbital decay
Orbital decay is the process of prolonged reduction in the altitude of a satellite's orbit.This can be due to drag produced by an atmosphere due to frequent collisions between the satellite and surrounding air molecules. The drag experienced by the object is larger in the case of increased solar...

. Two, vibration caused by mechanical systems and the crew on board the ISS. Three, orbital corrections by the on-board gyroscopes or thrusters. Four, the spatial separation from the real centre of mass
Center of mass
In physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...

 of the ISS. Any part of the ISS not at the exact center of mass will tend to follow its own orbit
Gravity-gradient stabilization
Gravity-gradient stabilization is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and the Earth's gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction...

. That is, parts on the underside, closer to the Earth are pulled harder, towards the Earth. Conversely, parts on the top of the station, further from Earth, try to fling off into space. However, as each point is physically part of the station, this is impossible, and so each component is subject to small forces which keep them attached to the station as it orbits. This is also called the tidal force
Tidal force
The tidal force is a secondary effect of the force of gravity and is responsible for the tides. It arises because the gravitational force per unit mass exerted on one body by a second body is not constant across its diameter, the side nearest to the second being more attracted by it than the side...

.

Researchers are investigating the effect of the station's near-weightless environment on the evolution, development, growth and internal processes of plants and animals. In response to some of this data, NASA wants to investigate microgravity's effects on the growth of three-dimensional, human-like tissues, and the unusual protein crystals that can be formed in space.

The investigation of the physics of fluids in microgravity will allow researchers to model the behaviour of fluids better. Because fluids can be almost completely combined in microgravity, physicists investigate fluids that do not mix well on Earth. In addition, an examination of reactions that are slowed by low gravity and temperatures will give scientists a deeper understanding of superconductivity
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...

.

The study of materials science
Materials science
Materials science is an interdisciplinary field applying the properties of matter to various areas of science and engineering. This scientific field investigates the relationship between the structure of materials at atomic or molecular scales and their macroscopic properties. It incorporates...

 is an important ISS research activity, with the objective of reaping economic benefits through the improvement of techniques used on the ground. Other areas of interest include the effect of the low gravity environment on combustion, through the study of the efficiency of burning and control of emissions and pollutants. These findings may improve current knowledge about energy production, and lead to economic and environmental benefits. Future plans are for the researchers aboard the ISS to examine aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

s, ozone
Ozone
Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

, water vapour
Water vapor
Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

, and oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

s in Earth's atmosphere, as well as cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s, cosmic dust
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...

, antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

, and dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 in the universe.

Exploration

The ISS provides a location in the relative safety of Low Earth Orbit to test spacecraft systems that will be required for long-duration missions to the Moon and Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

. This provides experience in the maintenance, repair, and replacement of systems on-orbit, which will be essential in operating spacecraft farther from Earth. Mission risks are reduced, and the capabilities of interplanetary spacecraft are advanced. The ESA states that "Whereas the ISS is essential for answering questions concerning the possible impact of weightlessness, radiation and other space-specific factors, other aspects such as the effect of long-term isolation and confinement can be more appropriately addressed via ground-based simulations".

A Mars exploration mission may be a multinational effort involving space agencies and countries outside the current ISS partnership. In 2010 ESA Director-General Jean-Jacques Dordain stated his agency was ready to propose to the other 4 partners that China, India and South Korea be invited to join the ISS partnership. NASA chief Charlie Bolden stated in Feb 2011 "Any mission to Mars is likely to be a global effort". As of 2011, the space agencies of Europe, Russia and China carried out the ground-based preparations in the Mars500 project, which complement the ISS-based preparations for a manned mission to Mars. China launched its own space station in September 2011, and has officially initiated its programme for a modular station. However, China has indicated a willingness to cooperate further with other countries on manned exploration.

Education and cultural outreach

The ISS crew provide opportunities for students on Earth by running student-developed experiments, making educational demonstrations, allowing for student participation in classroom versions of ISS experiments, and directly engaging students using radio, videolink and email. Cultural activities are another major objective. There is something about space that touches even people who are not interested in science.

Amateur Radio on the ISS (ARISS) is a volunteer programme which inspires students worldwide to pursue careers in science, technology, engineering and mathematics through amateur radio
Amateur radio
Amateur radio is the use of designated radio frequency spectrum for purposes of private recreation, non-commercial exchange of messages, wireless experimentation, self-training, and emergency communication...

 communications opportunities with the ISS crew. ARISS is an international working group, consisting of delegations from 9 countries including several countries in Europe as well as Japan, Russia, Canada, and the United States. In areas where radio equipment cannot be used, speakerphones connect students to ground stations which then connect the calls to the station.

JAXA aims both to 'Stimulate the curiosity of children, cultivating their spirits, and encouraging their passion to pursue craftsmanship', and to 'Heighten the child's awareness of the importance of life and their responsibilities in society.' Through a series of education guides, a deeper understanding of the past and near-term future of manned space flight, as well as that of Earth and life, will be learned. In the JAXA Seeds in Space experiments, the mutation effects of spaceflight on plant seeds aboard the ISS is explored. Students grow sunflower seeds which flew on the ISS for about nine months as a start to ‘touch the Universe’. In the first phase of kibo utilization from 2008 to mid-2010, researchers from more than a dozen Japanese universities conducted experiments in diverse fields.

ESA offers a wide range of free teaching materials that can be downloaded for use in classrooms. In one lesson, students can navigate a 3-D model of the interior and exterior of the ISS, and face spontaneous challenges to solve in real time.

First Orbit
First Orbit
First Orbit is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker...

 is a feature-length, experimental documentary film about Vostok 1, the first manned space flight around the Earth. By matching the orbit of the International Space Station to that of Vostok 1 as closely as possible, in terms of ground path and time of day, documentary filmmaker Christopher Riley and ESA astronaut Paolo Nespoli were able to film the view that Yuri Gagarin saw on his pioneering orbital space flight. This new footage was cut together with the original Vostok 1 mission audio recordings sourced from the Russian State Archive. Nespoli, during Expedition 26/27, filmed the majority of the footage for this documentary film, and as a result is credited as its director of photography
Cinematographer
A cinematographer is one photographing with a motion picture camera . The title is generally equivalent to director of photography , used to designate a chief over the camera and lighting crews working on a film, responsible for achieving artistic and technical decisions related to the image...

. The film was streamed through the website www.firstorbit.org in a global YouTube
YouTube
YouTube is a video-sharing website, created by three former PayPal employees in February 2005, on which users can upload, view and share videos....

 premiere in 2011, under a free license.

Origins

The International Space Station represents a combination of three national space station projects, NASA's Freedom, the RSA's Mir-2, and the European Columbus space stations. In September 1993, American Vice-President Al Gore, Jr., and Russian Prime Minister Viktor Chernomyrdin
Viktor Chernomyrdin
Viktor Stepanovich Chernomyrdin was the founder and the first chairman of the Gazprom energy company, the longest serving Prime Minister of Russia and Acting President of Russia for a day in 1996. He was a key figure in Russian politics in the 1990s, and a great contributor to the Russian...

 announced plans for a new space station, which eventually became the International Space Station. They also agreed, in preparation for this new project, that the United States would be involved in the Mir programme, including American Shuttles docking, in the Shuttle-Mir Program
Shuttle-Mir Program
The Shuttle–Mir Program was a collaborative space program between Russia and the United States, which involved American Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the shuttle and an American astronaut flying aboard a Soyuz spacecraft to engage in...

. According to the plan, the International Space Station programme would combine the proposed space stations of all participant agencies and the Japanese Kibō laboratory.

NASA's Freedom

In the early 1980s, NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...

 planned to launch a modular space station called Freedom as a counterpart to the Soviet Salyut and Mir space station
Space station
A space station is a spacecraft capable of supporting a crew which is designed to remain in space for an extended period of time, and to which other spacecraft can dock. A space station is distinguished from other spacecraft used for human spaceflight by its lack of major propulsion or landing...

s. Although approved by then-president Ronald Reagan and announced in the 1984 State of the Union Address, "We can follow our dreams to distant stars, living and working in space for peaceful economic and scientific gain", Freedom was never constructed or completed as originally designed, and after several cutbacks, the remnants of the project became part of the ISS. Several NASA Space Shuttle missions in the 1980s and early 1990s included spacewalks to demonstrate and test space station construction techniques.

NASA's first cost assessment in 1987 revealed the 'Dual Keel' Station would cost $14.5 billion. This caused a political uproar in Congress, and NASA and Reagan Administration officials reached a compromise in March 1987 which allowed the agency to proceed with a cheaper $12.2-billion Phase One Station that could be completed after 10 or 11 Shuttle assembly flights. This design initially omitted the $3.4-billion 'Dual Keel' structure and half of the power generators. The new Space Station configuration was named 'Freedom' by Reagan in June 1988. Originally, Freedom would have carried two 37.5 kW solar arrays. However, Congress quickly insisted on adding two more arrays for scientific users. The Space Station programme was plagued by conflicts during the entire 1984-87 definition phase. In 1987, the Department of Defense (DoD) briefly demanded to have full access to the Station for military research, despite strong objections from NASA and the international partners. Besides the expected furor from the international partners, the DoD position sparked a shouting match between Defense Secretary Caspar Weinberger and powerful members of Congress that extended right up to the final Fiscal 1988 budget authorization in July 1987. Reagan wanted to invite other NATO countries to participate in the U.S-led project, since the Soviet Union had been launching international crews to their Salyut space stations since 1971. At one point, then-anonymous disgruntled NASA employees calling themselves "Center for Strategic Space Studies" suggested that instead of building Freedom, NASA should take the back-up Skylab from display in the National Air and Space Museum in Washington and launch that.

The space station was also going to tie the emerging European and Japanese national space programmes closer to the U.S.-led project, thereby preventing those nations from becoming major, independent competitors too. An agreement signed in September 1988 allocated 97% of the US lab resources to NASA while the Canadian CSA would receive 3% in return for its contribution to the programme. Europe and Japan would retain 51% of their own laboratory modules. Six Americans and two international astronauts would be permanently based on Space Station Freedom.

Russia's Mir-2



The Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS or RS) is the eleventh Soviet-Russian space station. Mir and the ISS are successors to the Salyut and Almaz stations. Mir-2 was originally authorized in the February 1976 resolution setting forth plans for development of third generation Soviet space systems. The first MIR-2 module was launched in 1986 by an Energia
Energia
Energia was a Soviet rocket that was designed by NPO Energia to serve as a heavy-lift expendable launch system as well as a booster for the Buran spacecraft. Control system main developer enterprise was the NPO "Electropribor"...

 heavy-lift expendable launch system. The launcher worked properly, however the Polyus payload fired its engines to insert itself into orbit whilst in the wrong position due to a programming error, and re-entered the atmosphere. The planned station changed several times, but Zvezda was always the service module. The station would have used the Buran
Buran
Buran may refer to:* Buran , a Soviet space shuttle** Buran program, which developed the spacecraft* Buran eavesdropping device, invented by Léon Theremin, used by soviet intelligence* Buran cruise missile, a Soviet cruise missile...

 space shuttle and Proton rockets to lift new modules into orbit. The spaceframe of Zvezda, also called DOS-8 serial number 128, was completed in February 1985 and major internal equipment was installed by October 1986.

The Polyus module or spacecraft, which would have served the same function as Zarya, looked like a "Salyut" slightly modified for this task and was made up from parts of the ships "Cosmos-929, -1267, -1443, -1668" and from modules of MIR-2 station. There are two different descriptions of the weapon systems. In one, Polyus is described as a space-borne nuclear bomber, in another it is described as a satellite interceptor, carrying a 1 MegaWatt carbon dioxide laser. The module had a length of almost 37 m and a diameter of 4.1 m weighed nearly 80 t and included 2 principal sections, the smallest, the functional service block (FGB) and the largest, the aim module.

In 1983, the design was changed and the station would consist of Zvezda, followed by several 90 metric ton modules and a truss structure similar to the current station. The draft was approved by NPO Energia Chief Semenov on 14 December 1987 and announced to the press as 'Mir-2' in January 1988. This station would be visited by the Russian Space Shuttle Buran, but mainly resupplied by Progress-M2 spacecraft. Orbital assembly of the station was expected to begin in 1993. In 1993 with the collapse of the Soviet Union, a redesigned smaller Mir-2 was to be built whilst attached to Mir, just as OPSEK is being assembled whilst attached to the ISS.

Japan's Kibō

Conceived in 1985, the Japanese Experiment Module (JEM) or Kibō consists of a pressurized laboratory mainly dedicated to advanced technology experiments, a logistics module, an unpressurized pallet for vacuum experiments in space plus a robotic arm. While the proposed space station was redesigned many times around Kibō, the only significant change has been additional ballistic shielding, as its final position at the front of the station increases the risk of damage from debris. The Japanese National Space Development Agency (NASDA) formally submitted the JEM proposal to NASA in March 1986.

In 1986 the Japanese contribution was estimated to be worth $1.9-3.2 billion for a JEM launch in 1995. By 1990, the schedule had slipped by three years due to NASA budget cuts and space station cost overruns. The delays increased the JEM's total cost slightly, from $2.3 billion in 1986 to $2.63 billion in 1993, when the launch was postponed to 1999. Final hardware production began in the mid-1990s and the Japanese robotic arm was tested on a NASA Space Shuttle flight in August 1997. According to plans prior to the Columbia disaster, the JEM would be launched in 2002-03.


In 2010, Kibō won the Good Design Award, a year old consumer and industry award which identifies the best of Japanese craftsmanship. During August 2011, an observatory mounted on Kibō, which utilizes the ISS's orbital motion to image the whole sky in the X-ray spectrum, detected for the first time the moment a star was swallowed by a black hole.

ESA's Columbus

The Columbus Man-Tended Free Flyer (MTFF) was a European Space Agency
European Space Agency
The European Space Agency , established in 1975, is an intergovernmental organisation dedicated to the exploration of space, currently with 18 member states...

 (ESA) programme to develop a space station that could be used for a variety of microgravity experiments while serving ESA's needs for an autonomous manned space platform. The programme ran from 1986 to 1991, was expected to cost $3.56 billion including launch and utilization, and was cancelled while still in the planning stage. Aspects of the programme were later realised in the Columbus module.

In November 1992, further financial difficulties in Russia and uncertainties with America's Freedom space station led Russia and the European Space Agency to open discussions on joint development and use of Mir-2.

Station structure

The ISS is a 'third generation' or modular space station. Other examples of modular station projects include the Soviet/Russian MIR, Russian OPSEK, and Chinese Tiangong 3
Tiangong 3
Tiangong-3 will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency is expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module in 2013...

. The first space station, Salyut 1
Salyut 1
Salyut 1 was the first space station of any kind, launched by the USSR on April 19, 1971. It was launched unmanned using a Proton-K rocket. Its first crew came later in Soyuz 10, but was unable to dock completely; its second crew launched in Soyuz 11 and remained on board for 23 days...

, and other one-piece or 'monolithic' first generation space stations, such as Salyut 2,3,4,5, DOS 2, Kosmos 557, Almaz and NASA's Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

 stations were not designed for re-supply. Each crew had to depart the station to free the only docking port for the next crew to arrive. Second generation station projects such as Salyut 6 and 7 feature a second docking port. Third generation stations are modular stations, this allows the mission to be changed over time, new modules can be added or removed from the existing structure, saving considerable costs and allowing greater flexibility.

Below is a diagram of major station components. The blue areas are pressurized sections accessible by the crew without using spacesuits. The station's unpressurized superstructure is indicated in red. Other unpressurised components are yellow. Note that the Unity node joins directly to the Destiny laboratory. For clarity, they are shown apart.


Assembly


The assembly of the International Space Station, a major endeavour in space architecture
Space architecture
Space architecture, in its simplest definition, is the theory and practice of designing and building inhabited environments in outer space. The architectural approach to spacecraft design addresses the total built environment, drawing from diverse disciplines including physiology, psychology, and...

, began in November 1998. Russian modules launch and dock robotically, with the exception of Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

. All other modules were delivered by space shuttle, which required installation by ISS and shuttle crewmembers using the SSRMS and EVAs; , they had added 159 components during more than 1,000 hours of EVA activity. 127 of these spacewalks originated from the station, while the remaining 32 were launched from the airlocks of docked space shuttles. The beta angle
Beta angle
The beta angle is a value that is used most notably in spaceflight. The beta angle determines the percentage of time an object such as a spacecraft in low Earth orbit spends in direct sunlight, absorbing solar energy. Beta angle is defined as the angle between the orbit plane and the vector from...

 of the station had to be considered at all times during construction, as the station's beta angle is directly related to the percentage of its orbit that the station (as well as any docked or docking spacecraft) is exposed to the sun; the space shuttle would not perform optimally above a limit called the "beta cutoff". Rassvet was delivered by NASA's Atlantis Space Shuttle in 2010 in exchange for the Russian Proton delivery of the United States-funded Russian-built Zarya Module in 1998. Robot arms rather than EVAs were utilized in its installation (docking).

The first segment of the ISS, Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

, was launched on 20 November 1998 on an autonomous Russian Proton rocket. It provided propulsion, orientation control, communications, electrical power, but lacked long-term life support functions. Two weeks later a passive NASA module Unity was launched aboard Space Shuttle flight STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 and attached to Zarya by astronauts during EVAs. This module has two Pressurized Mating Adapter
Pressurized Mating Adapter
The International Space Station uses three Pressurized Mating Adapters to interconnect spacecraft and modules with different docking mechanisms. The first two PMAs were launched with the Unity module in 1998 aboard STS-88...

s (PMAs), one connects permanently to Zarya, the other allows the space shuttle to dock to the space station. At this time, the Russian station Mir was still inhabited. The ISS remained unmanned for two years, during which time Mir was de-orbited. On July 12, 2000 Zvezda was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive vehicle for a rendezvous with the Zarya and Unity. As a passive "target" vehicle, the Zvezda maintained a stationkeeping orbit as the Zarya-Unity vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. Zarya's computer transferred control of the station to Zvezda's computer soon after docking. Zvezda added sleeping quarters, a toilet, kitchen, CO2 scrubbers, dehumidifier, oxygen generators, exercise equipment, plus data, voice and television communications with mission control. This enabled permanent habitation of the station.

The first resident crew, Expedition 1
Expedition 1
Expedition 1, or Expedition One, was the first long-duration stay on the International Space Station . The three-person crew stayed aboard the station for 136 days, from November 2000 to March 2001. It was the beginning of an uninterrupted human presence on the station which still continues, as of...

, arrived in November 2000 on Soyuz TM-31
Soyuz TM-31
Soyuz TM-31 was the first Soyuz spacecraft to dock with the International Space Station . Launched near the end of 2000 the Soyuz-TM spacecraft brought to ISS Expedition 1, the first long-duration ISS crew...

, midway between the flights of STS-92
STS-92
STS-92 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Discovery. STS-92 marked the 100th mission of the Space Shuttle...

 and STS-97
STS-97
STS-97 was a Space Shuttle mission to the International Space Station flown by Space Shuttle Endeavour. The crew installed the first set of solar arrays to the ISS, prepared a docking port for arrival of the Destiny Laboratory Module, and delivered supplies for the station's crew.-Crew:-Mission...

. These two Space Shuttle flights each added segments of the station's Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

, which provided the station with Ku-band communication for U.S. television, additional attitude support needed for the additional weight of the USOS, and substantial solar arrays supplementing the station's existing 4 solar arrays.

Over the next two years the station continued to expand. A Soyuz-U
Soyuz-U
The Soyuz-U launch vehicle is an improved version of the original Soyuz LV. Soyuz-U is part of the R-7 family of rockets based on the R-7 Semyorka missile. Members of this rocket family were designed by the TsSKB design bureau and constructed at the Progress Factory in Samara, Russia....

 rocket delivered the Pirs docking compartment. The Space Shuttles Discovery, Atlantis
Space Shuttle Atlantis
The Space Shuttle Atlantis is a retired Space Shuttle orbiter in the Space Shuttle fleet belonging to the National Aeronautics and Space Administration , the spaceflight and space exploration agency of the United States...

, and Endeavour delivered the Destiny laboratory and Quest airlock, in addition to the station's main robot arm, the Canadarm2, and several more segments of the Integrated Truss Structure.

The expansion schedule was interrupted by the destruction of the on STS-107
STS-107
-Mission parameters:*Mass:**Orbiter Liftoff: **Orbiter Landing: **Payload: *Perigee: *Apogee: *Inclination: 39.0°*Period: 90.1 min- Insignia :...

 in 2003, with the resulting hiatus in the Space Shuttle program
Space Shuttle program
NASA's Space Shuttle program, officially called Space Transportation System , was the United States government's manned launch vehicle program from 1981 to 2011...

me halting station assembly until the launch of Discovery on STS-114
STS-114
-Original crew:This mission was to carry the Expedition 7 crew to the ISS and bring home the Expedition 6 crew. The original crew was to be:-Mission highlights:...

 in 2005.

The official resumption of assembly was marked by the arrival of Atlantis, flying STS-115
STS-115
Note:The P3/P4 Truss segment and batteries were so heavy that the crew count was reduced from seven to six.-Crew notes:...

, which delivered the station's second set of solar arrays. Several more truss segments and a third set of arrays were delivered on STS-116
STS-116
-Crew notes:Originally this mission was to carry the Expedition 8 crew to the ISS. The original crew was to be:-Mission highlights:* The STS-116 mission delivered and attached the International Space Station's third port truss segment, the P5 truss....

, STS-117
STS-117
- Crew Notes :The initial crew manifest before the Columbia accident was:Astronaut Mark Polansky was originally slated to pilot this mission, but was moved to STS-116, which he commanded...

, and STS-118
STS-118
- Crew notes :Astronaut Clayton Anderson originally was slated to be launched to the ISS on this mission, but was moved to STS-117. His replacement was Alvin Drew....

. As a result of the major expansion of the station's power-generating capabilities, more pressurised modules could be accommodated, and the Harmony node and Columbus European laboratory were added. These were followed shortly after by the first two components of Kibō. In March 2009, STS-119
STS-119
-Crew notes:This mission was originally scheduled to bring the Expedition 9 crew to the ISS. This crew would have consisted of:-Mission parameters:* Mass:* Orbiter liftoff: * Orbiter landing: * Perigee: * Apogee:...

 completed the Integrated Truss Structure with the installation of the fourth and final set of solar arrays. The final section of Kibō was delivered in July 2009 on STS-127
STS-127
STS-127 was a NASA Space Shuttle mission to the International Space Station . It was the twenty-third flight of . The primary purpose of the STS-127 mission was to deliver and install the final two components of the Japanese Experiment Module: the Exposed Facility , and the Exposed Section of the...

, followed by the Russian Poisk module. The third node, Tranquility, was delivered in February 2010 during STS-130
STS-130
STS-130 was a NASA Space Shuttle mission to the International Space Station . 's primary payloads were the Tranquility module and the Cupola, a robotic control station with six windows around its sides and another in the center, providing a 360-degree view around the station...

 by the Space Shuttle Endeavour, alongside the Cupola, closely followed in May 2010 by the penultimate Russian module, Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

, delivered by Space Shuttle Atlantis on STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

. The last pressurised module of the USOS, Leonardo, was brought to the station by Discovery on her final flight, STS-133
STS-133
STS-133 was the 133rd mission in NASA's Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discoverys 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011...

, followed by the Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 on STS-134
STS-134
STS-134 was the penultimate mission of NASA's Space Shuttle program. The mission marked the 25th and final flight of . This flight delivered the Alpha Magnetic Spectrometer and an ExPRESS Logistics Carrier to the International Space Station. Mark Kelly served as the mission commander...

, delivered by Endeavour.

, the station consisted of fifteen pressurised modules and the Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

. Still to be launched are the Russian Multipurpose Laboratory Module Nauka and a number of external components, including the European Robotic Arm
European Robotic Arm
The European Robotic Arm is a robotic arm to be attached to the Russian Segment of the International Space Station. It will be the first robot arm able to work on the Russian space station segments, and will supplement the two Russian Strela cargo cranes that are already installed on the Pirs...

. Assembly is expected to be completed by 2012, by which point the station will have a mass in excess of 400 metric tons (440 short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s).

The gross mass of the station is not possible to calculate with precision. The total launch weight of the modules on orbit is 417289 kilogram (as of 03/09/2011). The weight of experiments, spare parts, personal effects, crew, foodstuff, clothing, propellants, water supplies, gas supplies, docked spacecraft, and other items add to the total mass of the station. Gas (Hydrogen) is constantly vented overboard by the Oxygen generators.

Pressurised modules

Zarya
Zarya
Zarya , also known as the Functional Cargo Block or FGB , was the first module of the International Space Station to be launched. The FGB provided electrical power, storage, propulsion, and guidance to the ISS during the initial stage of assembly...

 , also known as the Functional Cargo Block or FGB , was the first module of the station, launched on November 20, 1998 on a Russian Proton rocket from Baikonur Cosmodrome Site 81
Baikonur Cosmodrome Site 81
Site 81 at the Baikonur Cosmodrome is a launch site used, along with Site 200, by Proton rockets. It consists of two launch pads, areas 23 and 24. Area 24 is currently used for Proton-K and Proton-M launches, while Area 23 is currently inactive....

 in Kazakhstan to a 400 km (248.5 mi) high orbit. After parking in orbit, the Zarya Module provided orientation control, communications and electrical power for itself, and for the passive Node 1 (Unity) attached later, while the station awaited launch of the third component, a Russian-provided crew living quarters and early station core, the service module Zvezda. The Service Module enhanced or replaced many functions of Zarya. The FGB is a descendant of the TKS spacecraft
TKS spacecraft
TKS spacecraft was a Soviet spacecraft design in the late 1960s intended to supply the military Almaz space station. The spacecraft was designed for manned or autonomous cargo resupply use...

 designed for the Russian Salyut
Salyut
The Salyut program was the first space station program undertaken by the Soviet Union, which consisted of a series of nine space stations launched over a period of eleven years from 1971 to 1982...

 programme. 6,100 kg of propellant fuel can be stored and transferred automatically to and from ships docked to the Russian portion of the station – the Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 (ROS). Zarya was originally intended as a module for the Russian Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 space station, but was not flown as of the end of the Mir-1 programme. Development costs for Zarya were paid for by Russia (and the former Soviet Union), spread across previous space station programmes, and some construction and preparation costs were paid for by the United States. Unity, a passive connecting module was the first U.S.-built component of the Station. It is cylindrical in shape, with six berthing locations facilitating connections to other modules. Unity was carried into orbit as the primary cargo of STS-88
STS-88
-Mission parameters:*Weight*Liftoff: *Landing: *Perigee: *Apogee: *Orbital Period: 92.4min-Launch attempts:-Mission highlights:Node 1, named Unity, was the first space station hardware delivered by the space shuttle. It has two Pressurized Mating Adapters , one attached to either end...

 in 1998.

Zvezda , DOS-8, also known as the Service Module or SM . It provides all of the station's critical systems, its addition rendered the station permanently habitable for the first time, adding life support for up to six crew and living quarters for two. Zvezda's DMS-R computer handles guidance, navigation & control for the entire space station. A second computer which performs the same functions is installed in the Nauka FGB-2. The rocket used for Zvezda's launch was one of the first to carry advertising
Space advertising
Space advertising is the use of advertising in outer space or related to space flight. While there have only been a few examples of successful marketing campaigns, there have been several proposals to advertise in space, some even planning to launch giant billboards visible from the Earth...

. The space frame was completed in February 1985, major internal equipment was installed by October 1986, and it was launched on 12 July 2000. Zvezda is at the rear of the station according to its normal direction of travel and orientation, its engines are used to boost the station's orbit. Alternatively Russian and European spacecraft can dock to Zvezda's aft (rear) port and use their engines to boost the station.

Destiny is the primary research facility for United States payloads aboard the ISS. In 2011, NASA solicited proposals for a not-for-profit group to manage all American science on the station which does not relate to manned exploration. The module houses 24 International Standard Payload Racks, some of which are used for environmental systems and crew daily living equipment. Destiny also serves as the mounting point for the station's Truss Structure.

Quest is the only USOS airlock, Quest hosts spacewalks with both United States EMU
Extravehicular Mobility Unit
The Space Shuttle/International Space Station Extravehicular Mobility Unit is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Space Shuttle or International Space Station crew member to perform extra-vehicular activity...

 and Russian Orlan spacesuits
Space suit
A space suit is a garment worn to keep an astronaut alive in the harsh environment of outer space. Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extra-vehicular activity , work done outside spacecraft...

. Quest consists of two segments; the equipment lock, that stores spacesuits and equipment, and the crew lock, from which astronauts can exit into space. This module has a separately controlled atmosphere. Crew sleep in this module, breathing a low nitrogen mixture the night before scheduled EVAs, to avoid decompression sickness (known as "the bends") in the low pressure suits.
Pirs ' onMouseout='HidePop("80530")' href="/topics/Pier">pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...

"), , and Poisk , also known as the Mini-Research Module
Mini-Research Module
International Space Station modules* Mini-Research Module 1 * Mini-Research Module 2 Other research modules of the Russian Orbital Segment:* Multipurpose Laboratory Module * Russian Research Modules...

 2 (MRM 2), , or МИМ 2. Pirs and Poisk are Russian airlock modules. Each of these modules have 2 identical hatches. An outward opening hatch on the MIR space station failed after it swung open too fast after unlatching, due to a small amount of air pressure remaining in the airlock. A different entry was used, and the hatch repaired. All EVA hatches on the ISS open inwards and are pressure sealing. Pirs is used to store, service, and refurbish Russian Orlan suits and provides contingency entry for crew using the slightly bulkier American suits. The outermost docking ports on both airlocks allow docking of Soyuz and Progress spacecraft, and the automatic transfer of propellants to and from storage on the ROS.

Harmony, is the second of the station's node modules and the utility hub of the USOS. The module contains four racks that provide electrical power, bus electronic data, and acts as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). The European Columbus and Japanese Kibō laboratories are permanently berthed to two of the radial ports, the other two can used for the HTV. American Shuttle Orbiters docked with the ISS via PMA-2, attached to the forward port. Tranquility is the third and last of the station's U.S. nodes, it contains an additional life support system to recycle waste water for crew use and supplements oxygen generation. Three of the four berthing locations are not used, one has the cupola installed and one has the docking port adapter installed.

Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

, the primary research facility for European payloads aboard the ISS, provides a generic laboratory
European Drawer Rack
The European Drawer Rack is a single, six-post International Standard Payload Rack with seven Experiment Modules , each of which has separate access to power and cooling. A Video Management Unit sends streaming video, images, and science data to Earth via the Columbus module's high-rate data...

 as well as facilities specifically designed for biology
Biolab
Biolab is a single-rack multi-user science payload designed for use in the Columbus laboratory of the International Space Station.Biolab does support biological research on small plants, small invertebrates, microorganisms, animal cells, and tissue cultures.It includes an incubator equipped with...

, biomedical research
European Physiology Modules
The European Physiology Module is an International Standard Payload Rack for the Columbus Laboratory on board the International Space Station. The EPM rack was built by OHB-System in Bremen....

 and fluid physics
Fluid Science Laboratory
The Fluid Science Laboratory is a European science payload designed for use in Columbus built by Alenia Aeronautica Spazio and OHB-System. It is a multi-user facility for conducting fluid physics research in microgravity conditions...

. Several mounting locations are affixed to the exterior of the module, which provide power and data to external experiments such as the European Technology Exposure Facility
European Technology Exposure Facility
The European Technology Exposure Facility is a payload mounted on the exterior of the European Columbus laboratory, one of the modules of the International Space Station...

 (EuTEF), Solar Monitoring Observatory
Solar Monitoring Observatory
The Solar Monitoring Observatory is an ESA science observatory that is part of the Columbus Laboratory, which is a component of the International Space Station. The Columbus module was launched February 2008 aboard STS-122. SOLAR was externally mounted to the Columbus Laboratory, together with...

, Materials International Space Station Experiment
Materials International Space Station Experiment
The Materials International Space Station Experiment , is a series of experiments mounted externally on the International Space Station that investigates the effects of long-term exposure of materials to the harsh space environment....

, and Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space is a project led by the European Space Agency which will place an ultra-stable atomic clock on the International Space Station...

. A number of expansions are planned for the module to study quantum physics and cosmology
Cosmology
Cosmology is the discipline that deals with the nature of the Universe as a whole. Cosmologists seek to understand the origin, evolution, structure, and ultimate fate of the Universe at large, as well as the natural laws that keep it in order...

.
Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

 ' onMouseout='HidePop("43727")' href="/topics/Hope">hope
Hope
Hope is the emotional state which promotes the belief in a positive outcome related to events and circumstances in one's life. It is the "feeling that what is wanted can be had or that events will turn out for the best" or the act of "look[ing] forward to with desire and reasonable confidence" or...

") is the largest single ISS module. This laboratory is used to carry out research in space medicine, biology, Earth observations, materials production, biotechnology, communications research, and has facilities for growing plants and fish. The laboratory contains a total of 23 racks, including 10 experiment racks and has a dedicated airlock for experiments. In a 'shirt sleeves' environment, crew attach an experiment to the sliding drawer within the airlock, close the inner, and then open the outer hatch. By extending the drawer and removing the experiment using the dedicated robotic arm, payloads are placed on the external platform. The process can be reversed and repeated quickly, allowing access to maintain external experiments without the delays caused by EVA's. Only the Russian and Japanese laboratories have this feature. A smaller pressurized module is attached to the top of Kibō, serving as a cargo bay. The dedicated Interorbital communications system allows large amounts of data to be beamed from Kibō's ICS, first to the Japanese KODAMA satellite in geostationary orbit, then to Japanese ground stations. When a direct communication link is used, contact time between the ISS and a ground station is limited to approximately 10 minutes per visible pass. When KODAMA relays data between a LEO spacecraft and a ground station, real-time communications are possible in 60% of the flight path of the spacecraft. Ground staff use tele-present robotics to conduct on-orbit research without crew intervention.

Cupola is an observatory, its seven windows are used to conduct experiments, observations of Earth and docking spacecraft. The Cupola project was started by NASA and Boeing, but canceled due to budget cuts. A barter agreement between NASA and the ESA resulted in the Cupola's development being resumed in 1998 by the ESA. The module comes equipped with robotic workstations for operating the station's main robotic arm and shutters to protect its windows from damage caused by micrometeorites. It features a 80 centimetres (31.5 in) round window, the largest window on the station.
Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

 , also known as the Mini-Research Module 1 (MRM-1) and formerly known as the Docking Cargo Module (DCM), is similar in design to the Mir Docking Module
Mir Docking Module
The Stykovochnyy Otsek , GRAU index 316GK, otherwise known as the Mir docking module or SO, was the sixth module of the Russian space station Mir, launched in November 1995 aboard the...

 launched on STS-74
STS-74
STS-74 was a Space Shuttle Atlantis mission to the Mir space station. It was the fourth mission of the US/Russian Shuttle-Mir Program, and it carried out the second docking of a space shuttle to Mir. Atlantis lifted off for the mission on 12 November 1995 from Kennedy Space Center launch pad 39A,...

 in 1995. Rassvet is primarily used for cargo storage and as a docking port for visiting spacecraft. It was flown to the ISS aboard NASA's on the STS-132
STS-132
STS-132 was a NASA Space Shuttle mission, during which Space Shuttle Atlantis docked with the International Space Station on 16 May 2010. STS-132 was launched from the Kennedy Space Center on 14 May 2010. The primary payload was the Russian Rassvet Mini-Research Module, along with an Integrated...

 mission and connected in May 2010, Rassvet is the only Russian owned module launched by NASA, to repay for the launch of Zarya, which is Russian designed and built, but partially paid for by NASA. Rassvet was launched with the Russian Nauka Laboratory's Experiments airlock temporarily attached to it, and spare parts for the European Robotic Arm.

Leonardo PPM The three NASA Space shuttle MPLM
Multi-Purpose Logistics Module
A Multi-Purpose Logistics Module is a large pressurized container used on Space Shuttle missions to transfer cargo to and from the International Space Station . An MPLM was carried in the cargo bay of a Shuttle and berthed to the Unity or Harmony modules on the ISS. From there, supplies were...

 cargo containers Leonardo, Raffaello and Donatello, were built for NASA in Turin
Turin
Turin is a city and major business and cultural centre in northern Italy, capital of the Piedmont region, located mainly on the left bank of the Po River and surrounded by the Alpine arch. The population of the city proper is 909,193 while the population of the urban area is estimated by Eurostat...

, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

 by Alcatel Alenia Space, now Thales Alenia Space
Thales Alenia Space
Thales Alenia Space is an aerospace company born after the Thales Group bought the participation of Alcatel in the two joint-ventures between Alcatel and Finmeccanica, Alcatel Alenia Space and Telespazio.-History:...

. The MPLMs are provided to the ISS programme by the Italy (independent of Italy's role as a member state of ESA) to NASA and are considered to be U.S. elements. In a bartered exchange for providing these containers, the U.S. has given Italy research time aboard the ISS out of the U.S. allotment in addition to that which Italy receives as a member of ESA. The Permanent Multipurpose Module was created by converting Leonardo into a module that could be permanently attached to the station.

Scheduled additional modules

Nauka , also known as the Multipurpose Laboratory Module (MLM) or FGB-2, (Russian
Russian language
Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

: Многофункциональный лабораторный модуль, or МЛМ), is the major Russian laboratory module. This module will be separated from the ISS before de-orbit with support modules and become the OPSEK space station, it contains an additional set of life support systems and orientation control, and power provided by its solar arrays will mean the ROS no longer relies on power from the USOS main arrays. Nauka's mission has changed over time, during the mid 1990's it was intended as a backup for the FGB, and later as a universal docking module (UDM), its docking ports will be able to support automatic docking of both space craft, additional modules and fuel transfer. Prior to the arrival of the MLM, a progress robot spacecraft will dock with PIRS, depart with that module, and both will be discarded. Nauka will then use its own engines to attach itself to the ROS in 2012.

Node Module
Node Module
The Node Module is a pressurized module of the Russian Segment of the International Space Station and will be used in the OPSEK space station...

 (UM)/(NM) This 4-ton ball shaped module will support the docking of two scientific and power modules during the final stage of the station assembly and provide the Russian segment additional docking ports to receive Soyuz TMA (transportation modified anthropometric) and Progress M spacecraft. NM is to be incorporated into the ISS in 2012. It will be integrated with a special version of the Progress cargo ship and launched by a standard Soyuz rocket. The Progress would use its own propulsion and flight control system to deliver and dock the Node Module to the nadir (Earth-facing) docking port of the Nauka MLM/FGB-2 module. One port is equipped with an active hybrid docking port, which enables docking with the MLM module. The remaining five ports are passive hybrids, enabling docking of Soyuz and Progress vehicles, as well as heavier modules and future spacecraft with modified docking systems. However more importantly, the node module was conceived to serve as the only permanent element of the future Russian successor to the ISS, OPSEK. Equipped with six docking ports, the Node Module would serve as a single permanent core of the future station with all other modules coming and going as their life span and mission required. This would be a progression beyond the ISS and Russia's modular MIR space station, which are in turn more advanced than early monolithic first generation stations such as Skylab, and early Salyut and Almaz stations.

Science Power Modules 1 & 2 (NEM-1, NEM-2)

Cancelled components


The US Habitation Module
Habitation Module
thumb|right|250px|ISS Habitation moduleThe Habitation Module for the International Space Station was intended to be the Station's main living quarters designed with galley, toilet, shower, sleep stations and medical facilities. About the size of a bus, the module was canceled after its pressurized...

 would have served as the station's living quarters. Instead, the sleep stations are now spread throughout the station. The US Interim Control Module
Interim Control Module
The Interim Control Module is a NASA constructed module designed to serve as a temporary "tug" for the International Space Station in case the Zvezda service module was destroyed or not launched for an extended period of time. It was derived from a formerly-classified Titan Launch Dispenser used...

 and ISS Propulsion Module
ISS Propulsion Module
The ISS Propulsion module was proposed as a backup to functions performed by the Zvezda Service Module and Progress spacecraft. Critical ISS functionality such as guidance, navigation, control and propulsion are provided only by Russian and future European assets...

 were intended to replace functions of Zvezda in case of a launch failure. The Russian Universal Docking Module
Universal Docking Module
The Nodal Module is a pressurized module of the Russian Segment of the International Space Station and will be used in the OPSEK space station...

, to which the cancelled Russian Research modules and spacecraft would have docked. The Russian Science Power Platform
Science Power Platform
The Science Power Platform was a planned Russian element of the International Space Station that was intended to be delivered to the ISS by a Russian Proton rocket or Zenit rocket but was shifted to launch by Space Shuttle as part as a tradeoff agreement on other parts of the ISS...

 would have provided the Russian Orbital Segment
Russian Orbital Segment
The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

 with a power supply independent of the ITS solar arrays, and two Russian Research Module
Russian Research Module
The Russian Research Module was to be a Russian component of the International Space Station that provided facilities for Russian science experiments and research...

s that were planned to be used for scientific research.

Unpressurised elements

The ISS features a large number of external components that do not require pressurization. The largest such component is the Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

 (ITS), to which the station's main solar arrays and thermal radiators are mounted. The ITS consists of ten separate segments forming a structure 108.5 m (356 ft) long.

The station in its complete form has several smaller external components, such as the six robotic arms, the three External Stowage Platform
External Stowage Platform
External Stowage Platforms are key components of the International Space Station . Each ESP is an external pallet that can hold spare parts, also known as Orbital Replacement Units , for the space station. As a platform it is not pressurized, but does require electricity to power the heaters of...

s (ESPs) and four ExPrESS Logistics Carriers
EXPRESS Logistics Carrier
An ExPRESS logistics carrier is an unpressurized attached payload platform for the International Space Station that provides mechanical mounting surfaces, electrical power, and command and data handling services for Orbital Replacement Units as well as science experiments on the ISS...

 (ELCs). Whilst these platforms allow experiments (including MISSE, the STP-H3 and the Robotic Refuelling Mission) to be deployed and conducted in the vacuum of space by providing electricity and processing experimental data locally, the platforms' primary function is to store Orbital Replacement Unit
Orbital replacement unit
Orbital Replacement Units are key elements of the International Space Station that can be readily replaced when the unit either passes its design life or fails. Examples of ORUs are: pumps, storage tanks, controller boxes, antennas, and battery units. Such units are replaced either by astronauts...

s (ORUs). ORUs are spare parts that can be replaced when the item either passes its design life or fails. Examples of ORUs include pumps, storage tanks, antennas and battery units. Such units are replaced either by astronauts during EVA or by robotic arms. While spare parts were routinely transported to and from the station via space shuttle resupply missions, there was a heavy emphasis on ORU transport once the station approached completion. Several shuttle missions were dedicated to the delivery of ORUs, including STS-129
STS-129
-Crew seat assignments:-Mission payload:-ExPRESS Logistics Carriers 1 and 2:The primary payload of STS-129 was the ExPRESS Logistics Carrier and the ELC-2. The mass capacity of each ELC is with a volume of 30 meters cubed...

, STS-133
STS-133
STS-133 was the 133rd mission in NASA's Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discoverys 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011...

 and STS-134
STS-134
STS-134 was the penultimate mission of NASA's Space Shuttle program. The mission marked the 25th and final flight of . This flight delivered the Alpha Magnetic Spectrometer and an ExPRESS Logistics Carrier to the International Space Station. Mark Kelly served as the mission commander...

. To date only one other mode of transportation of ORUs has been utilised – the Japanese cargo vessel HTV-2
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

 – which delivered an FHRC and CTC-2 via its Exposed Pallet (EP).

There are also smaller exposure facilities mounted directly to laboratory modules; the JEM Exposed Facility serves as an external 'porch
Porch
A porch is external to the walls of the main building proper, but may be enclosed by screen, latticework, broad windows, or other light frame walls extending from the main structure.There are various styles of porches, all of which depend on the architectural tradition of its location...

' for the Japanese Experiment Module complex, and a facility on the European Columbus laboratory provides power and data connections for experiments such as the European Technology Exposure Facility
European Technology Exposure Facility
The European Technology Exposure Facility is a payload mounted on the exterior of the European Columbus laboratory, one of the modules of the International Space Station...

 and the Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space
Atomic Clock Ensemble in Space is a project led by the European Space Agency which will place an ultra-stable atomic clock on the International Space Station...

. A remote sensing
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth by means of propagated signals Remote sensing...

 instrument, SAGE III-ISS
Stratospheric Aerosol and Gas Experiment
The Stratospheric Aerosol and Gas Experiment is a series of remote sensing satellite instruments used to study the chemical composition of earth's atmosphere. Specifically, SAGE has been used to study the Earth's ozone layer and aerosols at the troposhere through the stratosphere...

, is due to be delivered to the station in 2014 aboard a Dragon capsule
Dragon (spacecraft)
The Dragon is a reusable spacecraft developed by SpaceX, a private space transportation company based in Hawthorne, California. During its unmanned maiden flight in December 2010, it became the first commercially-built and -operated spacecraft to ever be successfully recovered from orbit.The Dragon...

. The largest such scientific payload externally mounted to the ISS is the Alpha Magnetic Spectrometer
Alpha Magnetic Spectrometer
The Alpha Magnetic Spectrometer, also designated AMS-02, is a particle physics experiment module that is mounted on the International Space Station. It is designed to search for various types of unusual matter by measuring cosmic rays. Its experiments will help researchers study the formation of...

 (AMS), a particle physics experiment, was launched on STS-134
STS-134
STS-134 was the penultimate mission of NASA's Space Shuttle program. The mission marked the 25th and final flight of . This flight delivered the Alpha Magnetic Spectrometer and an ExPRESS Logistics Carrier to the International Space Station. Mark Kelly served as the mission commander...

 in May 2011, and mounted externally on the ITS. The AMS measures cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s to look for evidence of dark matter
Dark matter
In astronomy and cosmology, dark matter is matter that neither emits nor scatters light or other electromagnetic radiation, and so cannot be directly detected via optical or radio astronomy...

 and antimatter
Antimatter
In particle physics, antimatter is the extension of the concept of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles...

.

Cranes and robotic arms


The largest robotic arm on the ISS, Canadarm2 has a mass of 1,800 kilograms and is used to dock and manipulate spacecraft and modules on the USOS, and hold crew members and equipment during EVAs. The ROS does not require spacecraft or modules to be manipulated, as all spacecraft and modules dock automatically, and may be discarded the same way. Crew use the 2 Strela
Strela (crane)
The Strela cranes are four cargo cranes used to move cosmonauts and components around the exterior of the Soviet/Russian space station Mir and the Russian Orbital Segment of the International Space Station...

cargo cranes during EVAs for moving crew and equipment around the ROS. Each Strela crane has a mass of 45 kg. The Russian and Japanese laboratories both have airlocks and robotic arms specifically to move science experiments quickly to or from the exposed space environment on the outside of the station to the shirt-sleeves pressurised environment within, where the crew can readily maintain the experiments without EVAs.

The Integrated Truss Structure
Integrated Truss Structure
the Integrated Truss Structure forms the backbone of the International Space Station, with mountings for unpressurized logistics carriers, radiators, solar arrays, and other equipment.-History:...

 serves as a base for the main remote manipulator system called the Mobile Servicing System (MSS). This consists of the Mobile Base System (MBS), the Canadarm2, and the Special Purpose Dexterous Manipulator. The MBS rolls along rails built into some of the ITS segments to allow the arm to reach all parts of the United States segment of the station. The MSS had its reach increased an Orbiter Boom Sensor System
Orbiter Boom Sensor System
The Orbiter Boom Sensor System is a 50-foot boom carried on board NASA's Space Shuttles. The boom can be grappled by the Canadarm and serves as an extension of the arm, doubling its length to a combined total of 100 feet...

 in May 2011, used to inspect tiles on the NASA shuttle, and converted for permanent station use. To gain access to the extreme extents of the Russian Segment the crew also placed a "Power Data Grapple Fixture" to the forward docking section of Zarya, so that the Canadarm2 may inchworm itself onto that point.

The European Robotic Arm
European Robotic Arm
The European Robotic Arm is a robotic arm to be attached to the Russian Segment of the International Space Station. It will be the first robot arm able to work on the Russian space station segments, and will supplement the two Russian Strela cargo cranes that are already installed on the Pirs...

, which will service the Russian Orbital Segment, will be launched alongside the Multipurpose Laboratory Module
Multipurpose Laboratory Module
Nauka , also known as the Multipurpose Laboratory Module , , will be a component of the International Space Station , funded by the Russian Federal Space Agency. In the original ISS plans, Nauka was to use the location of the Docking and Stowage Module...

 in 2012. The Japanese Experiment Module's Remote Manipulator System (JFM RMS), which services the JEM Exposed Facility, was launched on STS-124
STS-124
STS-124 was a Space Shuttle mission, flown by Space Shuttle Discovery to the International Space Station. Discovery launched on 31 May 2008 at 17:02 EDT, moved from an earlier scheduled launch date of 25 May 2008, and landed safely at the Kennedy Space Center's Shuttle Landing Facility, at 11:15...

 and is attached to the JEM Pressurised Module.

Life support

The critical systems are the atmosphere control system, the water supply system, the food supply facilities, the sanitation and hygiene equipment, and fire detection and suppression equipment. The Russian orbital segment's life support systems are contained in the Service Module Zvezda. Some of these systems are supplemented by equipment in the USOS. The MLM Nauka laboratory has a complete set of life support systems.

Atmospheric control systems

The atmosphere on board the ISS is similar to the Earth's. Normal air pressure on the ISS is 101.3 kPa (14.7 psi
Pounds per square inch
The pound per square inch or, more accurately, pound-force per square inch is a unit of pressure or of stress based on avoirdupois units...

); the same as at sea level on Earth. An Earth-like atmosphere offers benefits for crew comfort, and is much safer than the alternative, a pure oxygen atmosphere, because of the increased risk of a fire such as that responsible for the deaths of the Apollo 1
Apollo 1
Apollo 1 was scheduled to be the first manned mission of the Apollo manned lunar landing program, with a target launch date of February 21, 1967. A cabin fire during a launch pad test on January 27 at Launch Pad 34 at Cape Canaveral killed all three crew members: Command Pilot Virgil "Gus"...

 crew. Earth-like atmospheric conditions have been maintained on all Russian spacecraft.

ECLSS controls atmospheric pressure
Atmospheric pressure
Atmospheric pressure is the force per unit area exerted into a surface by the weight of air above that surface in the atmosphere of Earth . In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point...

, fire detection and suppression, oxygen levels, waste management and water supply. The highest priority for the ECLSS is maintaining the onboard atmosphere, but the system also collects, processes, and stores waste and water produced and used by the crew—a process that recycles water from the sink and toilet, and condensation from the air. The Elektron system aboard Zvezda and a similar system in Destiny generate oxygen aboard the station. The crew has a backup option in the form of bottled oxygen and Solid Fuel Oxygen Generation
Chemical oxygen generator
A chemical oxygen generator is a device releasing oxygen created by a chemical reaction. The oxygen source is usually an inorganic superoxide, chlorate, or perchlorate. A promising group of oxygen sources are ozonides. The generators are usually ignited mechanically, by a firing pin, and the...

 (SFOG) canisters. Carbon dioxide is removed from the air by the Vozdukh system in Zvezda. Other by-products of human metabolism, such as methane from the intestines and ammonia from sweat, are removed by activated charcoal
Activated carbon
Activated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.The word activated in the name is sometimes replaced...

 filters.

Part of the ROS atmosphere control system is the oxygen supply, triple-redundancy is provided by the Elektron unit, solid fuel generators, and stored oxygen. The Elektron unit is the primary oxygen supply, and are produced by electrolysis, with the being vented overboard. The 1kW system uses approximately 1 liter of water per crew member per day from stored water from Earth, or water recycled from other systems. MIR was the first spacecraft to use recycled water for oxygen production. The secondary oxygen supply is provided by burning producing Vika cartridges. Each 'candle' takes 5–20 minutes to decompose at 450–500 °C, producing 600 liters of , this unit is manually operated..

The US orbital segment has redundant supplies of oxygen, from a pressurized storage tank on the Quest airlock module delivered in 2001, supplemented ten years later by ESA built Advanced Closed-Loop System (ACLS) in the Tranquility module (Node 3), which produces by electrolysis. Hydrogen produced is combined with Carbon dioxide from the cabin atmosphere and converted to water and methane.

Food

Most of the food
Space food
Space food is food products, specially created and processed for consumption by astronauts in outer space. The food has specific requirements of providing balanced nutrition for the health of individuals working in space, while being easy and safe to store, prepare and consume in the machinery...

 eaten by station crews is stored frozen, refrigerated or canned. Menus are prepared by the astronauts, with the help of a dietitian
Dietitian
Dietitians supervise the preparation and service of food, develop modified diets, participate in research, and educate individuals and groups on good nutritional habits. The goals of dietitians are to provide medical nutritional intervention, and to obtain, safely prepare, serve and advise on...

, before the astronauts' flight to the station. As the sense of taste is reduced in orbit because of fluid shifting to the head, spicy food is a favourite of many crews. Each crewmember has individual food packages and cooks them using the onboard galley, which features two food warmers, a refrigerator, and a water dispenser that provides both heated and unheated water. Drinks are provided in dehydrated powder form and are mixed with water before consumption. Drinks and soups are sipped from plastic bags with straws, while solid food is eaten with a knife and fork, which are attached to a tray with magnets to prevent them from floating away. Any food that does float away, including crumbs, must be collected to prevent it from clogging up the station's air filters and other equipment.

Hygiene

The ISS does not feature a shower, although it was planned as part of the now cancelled Habitation Module
Habitation Module
thumb|right|250px|ISS Habitation moduleThe Habitation Module for the International Space Station was intended to be the Station's main living quarters designed with galley, toilet, shower, sleep stations and medical facilities. About the size of a bus, the module was canceled after its pressurized...

. Instead, crewmembers wash using a water jet and wet wipes, with soap dispensed from a toothpaste tube-like container. Crews are also provided with rinseless shampoo and edible toothpaste to save water.

There are two space toilet
Space toilet
A space toilet, or zero gravity toilet, is a toilet that can be used in a weightless environment. In the absence of weight the collection and retention of liquid and solid waste is directed by use of air flow. Since the air used to direct the waste is returned to the cabin, it is filtered...

s on the ISS, both of Russian design, located in Zvezda and Tranquility. These Waste and Hygiene Compartments use a fan-driven suction system similar to the Space Shuttle Waste Collection System. Astronauts first fasten themselves to the toilet seat, which is equipped with spring-loaded restraining bars to ensure a good seal. A lever operates a powerful fan and a suction hole slides open: the air stream carries the waste away. Solid waste is collected in individual bags which are stored in an aluminium container. Full containers are transferred to Progress spacecraft for disposal. Liquid waste is evacuated by a hose connected to the front of the toilet, with anatomically correct "urine funnel adapters" attached to the tube so both men and women can use the same toilet. Waste is collected and transferred to the Water Recovery System, where it is recycled back into drinking water.

Power supply


Double-sided solar, or Photovoltaic arrays, provide electrical power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...

 for the ISS. These bifacial cells are more efficient and operate at a lower temperature than single-sided cells commonly used on Earth, by collecting sunlight on one side and light reflected off
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

 the Earth on the other.

The Russian segment of the station, like the space shuttle and most spacecraft, uses 28 volt
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...

 DC
Direct current
Direct current is the unidirectional flow of electric charge. Direct current is produced by such sources as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type. Direct current may flow in a conductor such as a wire, but can also flow through...

 from four rotating solar arrays mounted on Zarya and Zvezda. The USOS uses 130–180 V DC from the USOS PV array.

The USOS solar arrays are arranged as four wing pairs, with each wing producing nearly 32.8 kW
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...

. These arrays normally track the sun to maximise power generation. Each array is about 375 m2 (450 yd2) in area and 58 metres (63 yd) long. In the complete configuration, the solar arrays track the sun by rotating the alpha gimbal
Gimbal
A gimbal is a pivoted support that allows the rotation of an object about a single axis. A set of two gimbals, one mounted on the other with pivot axes orthogonal, may be used to allow an object mounted on the innermost gimbal to remain immobile regardless of the motion of its support...

once per orbit while the beta gimbal follows slower changes in the angle of the sun to the orbital plane. The Night Glider mode
Night Glider mode
Night Glider mode is one of the procedures for orienting the solar arrays on the International Space Station.Normally the photovoltaic solar arrays of the space station track the sun...

 aligns the solar arrays parallel to the ground at night to reduce the significant aerodynamic drag at the station's relatively low orbital altitude.

The station uses rechargeable nickel-hydrogen batteries
Nickel hydrogen battery
A nickel–hydrogen battery is a rechargeable electrochemical power source based on nickel and hydrogen. It differs from a nickel–metal hydride battery by the use of hydrogen in a pressurized cell at up to 1200 psi pressure.The cathode is made up of a dry sintered porous nickel plaque, which...

 (NiH2) for continuous power during the 35 minutes of every 90 minute orbit that it is eclipsed by the Earth. The batteries are recharged on the day side of the Earth. They have a 6.5 year lifetime (over 37,000 charge/discharge cycles) and will be regularly replaced over the anticipated 20-year life of the station. In the USOS, power is stabilised and distributed at 160 V DC and converted to the user-required 124 V DC. The higher distribution voltage
High voltage
The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements...

 allows smaller, lighter conductors, at the expense of crew safety. The ROS uses low voltage. The two station segments share power with converters.

The station's large solar panels generate a high potential voltage difference between the station and the ionosphere. This could cause arcing through insulating surfaces and sputtering of conductive surfaces as ions are accelerated by the spacecraft plasma sheath. To mitigate this, plasma contactor units (PCU)s create current paths between the station and the ambient plasma field.

Thermal Control System

The large amount of electrical power consumed by the station's systems and experiments is turned almost entirely into heat. The heat which can be dissipated through the walls of the stations modules is insufficient to keep the internal ambient temperature within comfortable, workable limits. Ammonia is continuously pumped through pipework throughout the station to collect heat, and then into external radiators exposed to the cold of space, and back into the station.

The International Space Station (ISS) External Active Thermal Control System (EATCS) maintains an equilibrium when the ISS environment or heat loads exceed the capabilities of the Passive Thermal Control System (PTCS). Note Elements of the PTCS are external surface materials, insulation such as MLI, or Heat Pipes. The EATCS provides heat rejection capabilities for all the US pressurised modules, including the JEM and COF as well as the main power distribution electronics of the S0, S1 and P1 Trusses. The EATCS consists of two independent Loops (Loop A & Loop B), they both use mechanically pumped Ammonia in fluid state, in closed-loop circuits. The EATCS is capable of rejecting up to 70 kW, and provides a substantial upgrade in heat rejection capacity from the 14 kW capability of the Early External Active Thermal Control System (EEATCS) via the Early Ammonia Servicer (EAS), which was launched on STS-105
STS-105
STS-105 was a mission of the Space Shuttle Discovery to the International Space Station, launched from Kennedy Space Center, Florida, 10 August 2001. This mission was Discoverys final mission until STS-114, because Discovery was grounded for a refit, and then all Shuttles were grounded in the wake...

 and installed onto the P6 Truss.

Communications & computers

Radio communications
Radio
Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 provide telemetry
Telemetry
Telemetry is a technology that allows measurements to be made at a distance, usually via radio wave transmission and reception of the information. The word is derived from Greek roots: tele = remote, and metron = measure...

 and scientific data links between the station and Mission Control Centres
Mission Control Center
A mission control center is an entity that manages aerospace vehicle flights, usually from the point of lift-off until the landing or the end of the mission. A staff of flight controllers and other support personnel monitor all aspects of the mission using telemetry, and send commands to the...

. Radio links are also used during rendezvous and docking procedures
Space rendezvous
A space rendezvous is an orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance . Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain at a constant...

 and for audio and video communication between crewmembers, flight controllers and family members. As a result, the ISS is equipped with internal and external communication systems used for different purposes.


The Russian Orbital Segment communicates directly with the ground via the Lira
Lira (ISS)
The Lira system is a two-way communication system used between the International Space Station and Mission Control via the Russian Luch relay satellite constellation, also known as Altair....

 antenna
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

 mounted to Zvezda. The Lira antenna also has the capability to use the Luch data relay satellite system. This system, used for communications with Mir, fell into disrepair during the 1990s, and as a result is no longer in use, although two new Luch satellites—Luch-5A and Luch-5B—are planned for launch in 2011 to restore the operational capability of the system. Another Russian communications system is the Voskhod-M
Voskhod-M
The Voskhod-M is an audio subsystem on the International Space Station designed to provide radio communications between crewmembers and the ground or nearby Soyuz spacecraft...

, which enables internal telephone communications between Zvezda, Zarya, Pirs, Poisk and the USOS, and also provides a VHF radio link to ground control centres via antennas on Zvezdas exterior.

The US Orbital Segment
US Orbital Segment
The US Orbital Segment is the name given to the components of the International Space Station constructed and operated by the US National Aeronautics and Space Administration , European Space Agency , Canadian Space Agency and Japan Aerospace Exploration Agency .The segment currently consists of...

 (USOS) makes use of two separate radio links mounted in the Z1 truss structure: the S band
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...

 (used for audio) and Ku band
Ku band
The Kμ band is a portion of the electromagnetic spectrum in the microwave range of frequencies. This symbol refers to —in other words, the band directly below the K-band...

 (used for audio, video and data) systems. These transmissions are routed via the United States Tracking and Data Relay Satellite
Tracking and Data Relay Satellite
A Tracking and Data Relay Satellite is a type of communications satellite that forms part of the Tracking and Data Relay Satellite System used by NASA and other United States government agencies for communications to and from independent "User Platforms" such as satellites, balloons, aircraft,...

 System (TDRSS) in geostationary orbit
Geostationary orbit
A geostationary orbit is a geosynchronous orbit directly above the Earth's equator , with a period equal to the Earth's rotational period and an orbital eccentricity of approximately zero. An object in a geostationary orbit appears motionless, at a fixed position in the sky, to ground observers...

, which allows for almost continuous real-time communications with NASA's Mission Control Center (MCC-H) in Houston. Data channels for the Canadarm2, European Columbus laboratory and Japanese Kibō modules are routed via the S band and Ku band systems, although the European Data Relay Satellite
European Data Relay Satellite
The European Data Relay Satellite system will be a constellation of GEO satellites intended to relay information between other satellites and ground stations, to allow full-time communications even with satellites in low-Earth orbit which are often not visible from any European-operated ground...

 System and a similar Japanese system will eventually complement the TDRSS in this role. Communications between modules are carried on an internal digital wireless network
Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...

.

UHF radio
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...

 is used by astronauts and cosmonauts conducting EVAs
Extra-vehicular activity
Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...

. UHF is employed by other spacecraft that dock to or undock from the station, such as Soyuz, Progress, HTV, ATV and the Space Shuttle (except the shuttle also makes use of the S band and Ku band systems via TDRSS), to receive commands from Mission Control and ISS crewmembers. Automated spacecraft are fitted with their own communications equipment; the ATV uses a laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 attached to the spacecraft and equipment attached to Zvezda, known as the Proximity Communications Equipment, to accurately dock to the station.

The ISS is equipped with approximately 100 IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 and Lenovo ThinkPad model A31 and T61P laptop computers. Each computer is a commercial off-the-shelf
Commercial off-the-shelf
In the United States, Commercially available Off-The-Shelf is a Federal Acquisition Regulation term defining a nondevelopmental item of supply that is both commercial and sold in substantial quantities in the commercial marketplace, and that can be procured or utilized under government contract...

 purchase which is then modified for safety and operation including updates to connectors, cooling and power to accommodate the station's 28V DC power system and weightless environment. Laptops aboard the ISS are connected to the station's wireless LAN
Wireless LAN
A wireless local area network links two or more devices using some wireless distribution method , and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network...

 via Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...

 and are connected to the ground at 3 Mbit/s up and 10 Mbit/s down, comparable to home DSL
Digital Subscriber Line
Digital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...

 connection speeds.

Docking

Spacecraft from Russia and Europe are able to launch and fly themselves without human intervention, both Russian manned and unmanned spacecraft dock using the automated Kurs radio telemetry system
Kurs (docking system)
Kurs is a radio telemetry system used by the Soviet and later Russian space program.Kurs was developed by the Research Institute of Precision Instruments before 1985 and manufactured by the Kiev Radio Factory .- History :...

, this is comparable to the docking system used on the Chinese Tiangong-1. The American Space Shuttle was manually docked, and on missions with a Multi-Purpose Logistics Module
Multi-Purpose Logistics Module
A Multi-Purpose Logistics Module is a large pressurized container used on Space Shuttle missions to transfer cargo to and from the International Space Station . An MPLM was carried in the cargo bay of a Shuttle and berthed to the Unity or Harmony modules on the ISS. From there, supplies were...

, the MPLM would be berthed to the Station with the use of manually controlled robot arms. The Japanese H-II Transfer Vehicle
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

 parks itself in progressively closer orbits to the station, and then awaits 'approach' commands from the crew, until it is close enough for the crew to grapple it with a robotic arm and berth it to the USOS. Berthed craft can transfer International Standard Payload Racks. Japanese spacecraft berth for 1–2 months. Russian and European Supply craft can remain at the ISS for 6 months, allowing great flexibility in crew time for loading and unloading of supplies and trash. NASA Shuttles could remain docked for 11-12 days.

The American Manual approach to docking allows greater initial flexibility and less complexity. The downside to this mode of operation is that each mission becomes unique and requires specialized training and planning, making the process more labor-intensive and expensive. The Russians pursued an automated methodology that used the crew in override or monitoring roles. Although the initial development costs were high, the system has become very reliable with standardizations that provide significant cost benefits in repetitive routine operations. The Russian approach allows assembly of space stations orbiting other worlds in preparation for manned missions. The Nauka module of the ISS will be used in the 12th Russian(/Soviet) space station, OPSEK, whose main goal is supporting manned deep space exploration.
Soyuz manned spacecraft for crew rotation also serve as lifeboats for emergency evacuation, they are replaced every six months and have been used once to remove excess crew after the Columbia disaster. Expeditions require, on average, of supplies, and , crews had consumed a total of around . Soyuz crew rotation flights and Progress resupply flights visit the station on average two and three times respectively each year, with the ATV and HTV planned to visit annually from 2010 onwards. Following retirement of the NASA Shuttle Cygnus
Cygnus spacecraft
The Cygnus spacecraft is an unmanned resupply spacecraft being developed by Orbital Sciences Corporation and Thales Alenia Space as part of NASA's COTS project. It is designed to transport supplies to the International Space Station after the retirement of the Space Shuttle...

 and Dragon will fly cargo to the station until at least 2015.

From 26 February 2011 to 7 March 2011, during STS-133
STS-133
STS-133 was the 133rd mission in NASA's Space Shuttle program; during the mission, Space Shuttle Discovery docked with the International Space Station. It was Discoverys 39th and final mission. The mission launched on 24 February 2011, and landed on 9 March 2011...

, four of the governmental partners (United States, ESA, Japan and Russia) had their spacecraft (NASA Shuttle, ATV, HTV, Progress and Soyuz) docked at the ISS, the only time this has happened to date.

Currently docked

Spacecraft Mission Docking port Docked (UTC) Undocking (UTC) Notes
  Progress M-13M
Progress M-13M
Progress M-13M , identified by NASA as Progress 45 or 45P, is a Progress spacecraft which reached the International Space Station on 2 November 2011. The Progress M-13M spacecraft lifted off from the Baikonur Cosmodrome in Kazakhstan at 10:11 GMT on 30 October, starting off the 45th unmanned...

Progress 45 Cargo Pirs 2 November 2011 11:41 25 January 2012
  Soyuz TMA-22
Soyuz TMA-22
Soyuz TMA-22 is a current flight to the International Space Station . TMA-22 was the 111th flight of a Soyuz spacecraft, and transported three members of the Expedition 29 crew to the ISS...

Expedition 29
Expedition 29
Expedition 29 was the 29th long-duration expedition to the International Space Station . The expedition formally began with the departure from the ISS of the Soyuz TMA-21 spacecraft at 00:38 UTC on on 16 September 2011...

/30
Expedition 30
Expedition 30 is the 30th and current long-duration mission to the International Space Station . The expedition's first three crew members – Dan Burbank, Anton Shkaplerov and Anatoli Ivanishin – arrived on the ISS aboard Soyuz TMA-22 on 16 November 2011, during the last phase of...

Poisk 16 November 2011 05:24

Scheduled launches and dockings

, there have been 25 Soyuz, 41 Progress, 2 ATV, 2 HTV and 35 space shuttle flights to the station.

All dates are UTC. Dates are the earliest possible dates and may change.
Forward ports are at the front of the station according to its normal direction of travel and orientation (attitude). Aft is at the rear of the station, used by spacecraft boosting the station's orbit. Nadir
Nadir
The nadir is the direction pointing directly below a particular location; that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous...

 is closest the Earth, Zenith
Zenith
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere. "Above" means in the vertical direction opposite to the apparent gravitational force at that location. The opposite direction, i.e...

 is on top.
Spacecraft Launch Mission Planned docking Docking port Notes
  Soyuz TMA-03M
Soyuz TMA-03M
Soyuz TMA-03M is a planned 2011 flight to the International Space Station. It will transport three members of the Expedition 30 crew to the International Space Station. TMA-03M will be the 112th flight of a Soyuz spacecraft, the first flight launching in 1967, and the third flight of the modernised...

21 December 2011 Expedition 30
Expedition 30
Expedition 30 is the 30th and current long-duration mission to the International Space Station . The expedition's first three crew members – Dan Burbank, Anton Shkaplerov and Anatoli Ivanishin – arrived on the ISS aboard Soyuz TMA-22 on 16 November 2011, during the last phase of...

/31
Expedition 31
Expedition 31 is scheduled to be the thirty-first expedition to the International Space Station.-Crew:Source: NASA-External links:**...

23 December 2011 Rassvet
Rassvet (ISS module)
Rassvet , also known as the Mini-Research Module 1 and formerly known as the Docking Cargo Module , is a component of the International Space Station . The module's design is similar to the Mir Docking Module launched on STS-74 in 1995. Rassvet is primarily used for cargo storage and as a docking...

  Dragon C2 12 January 2012 Dragon Demo TBD Harmony nadir
  Progress M-14M
Progress-M1
Progress-M1 , also known as Progress 7K-TGM1, is a Russian spacecraft which is used to resupply space stations. It is a variant of the Progress spacecraft, derived from the Progress-M, but modified to carry more propellent for refuelling the space station instead of other cargoes such as water...

TBD Progress 46 Cargo TBD Pirs
  White Stork 3
H-II Transfer Vehicle
The H-II Transfer Vehicle , called , is an unmanned resupply spacecraft used to resupply the Kibō Japanese Experiment Module and the International Space Station . The Japan Aerospace Exploration Agency has been working on the design since the early 1990s. The first mission, HTV-1, was originally...

18 February 2012 HTV-3 Cargo 23 February 2012 Harmony
  Cygnus 1 23 February 2012 Cygnus 1 Cargo TBD Harmony nadir
  Edoardo Amaldi
Edoardo Amaldi ATV
The Edoardo Amaldi ATV, or Automated Transfer Vehicle 003 , is a European unmanned cargo resupply spacecraft named after Italian physicist Edoardo Amaldi. The spacecraft is scheduled for launch in 2012, on a mission to supply the International Space Station with propellant, water, air, and dry cargo...

7 March 2012 ATV-3 Cargo 15 March 2012 Zvezda aft
  Soyuz TMA-04M
Soyuz TMA-04M
Soyuz TMA-04M is a planned 2012 flight to the International Space Station. It will transport three members of the Expedition 31 crew to the International Space Station. TMA-04M will be the 113th flight of a Soyuz spacecraft, the first flight launching in 1967...

30 March 2012 Expedition 31
Expedition 31
Expedition 31 is scheduled to be the thirty-first expedition to the International Space Station.-Crew:Source: NASA-External links:**...

/32
Expedition 32
Expedition 32 is scheduled to be the thirty-second expedition to the International Space Station.-Crew:Source: NASA-External links:**...

TBD Poisk
  Dragon C3
Dragon (spacecraft)
The Dragon is a reusable spacecraft developed by SpaceX, a private space transportation company based in Hawthorne, California. During its unmanned maiden flight in December 2010, it became the first commercially-built and -operated spacecraft to ever be successfully recovered from orbit.The Dragon...

12 April 2012 Dragon 1 Cargo TBD TBD
  Proton May 2012 Module Nauka MLM May 2012
  Progress M-UM with Soyuz-2.1b 2012 Module Node Module (UM) 2012
  Proton-M (or Angara A5) 2014 Module NEM-1 2014
  Proton-M (or Angara A5) 2015 Module NEM-2 2015

TBD = Yet to be decided/determined.

Expeditions

Each permanent crew is given an expedition number. Expeditions have an average duration of half a year, and they commence following the official handover of the station from one Expedition commander to another. Expeditions 1 through 6 consisted of three person crews, but the Columbia accident led to a reduction to two crew members for Expeditions 7 to 12. Expedition 13
Expedition 13
Expedition 13 was the 13th expedition to the International Space Station , and launched at 02:30 UTC on 30 March 2006. The expedition used the Soyuz TMA-8 spacecraft, which stayed at the station for the duration of the expedition for emergency evacuation....

 saw the restoration of the station crew to at least three. Several expeditions, such as Expedition 16
Expedition 16
Expedition 16 was the 16th expedition to the International Space Station .The first two crew members, Yuri Malenchenko and Peggy Whitson, launched on 10 October 2007, aboard Soyuz TMA-11, and were joined by spaceflight participant Sheikh Muszaphar Shukor, the first Malaysian in space.Expedition 15...

, have consisted of up to six Crew members, who are flown to and from the station on separate flights. When crew size was increased to six in 2010, space tourism was halted until 2013. With the arrival of the American Commercial Crew
Commercial Crew Development
Commercial Crew Development is a multiphase space technology development program, funded by the U.S. government, and administered by NASA. The program is intended to stimulate development of privately operated crew vehicles to low Earth orbit. It is run by the Commercial Crew and Cargo Program...

 vehicles in the middle of the 2010s, expedition size may be increased to seven crew members, the number ISS is designed for.

The International Space Station is the most-visited spacecraft in the history of space flight. , it had received 297 visitors (196 different people). Mir had 137 visitors (104 different people).

Work

A typical day for the crew begins with a wake-up at 06:00, followed by post-sleep activities and a morning inspection of the station. The crew then eats breakfast and takes part in a daily planning conference with Mission Control before starting work at around 08:10. The first scheduled exercise of the day follows, after which the crew continues work until 13:05. Following a one-hour lunch break, the afternoon consists of more exercise and work before the crew carries out its pre-sleep activities beginning at 19:30, including dinner and a crew conference. The scheduled sleep period begins at 21:30. In general, the crew works ten hours per day on a weekday, and five hours on Saturdays, with the rest of the time their own for relaxation or work catch-up.

The station provides crew quarters for each member of the expedition's crew, with two 'sleep stations' in the Zvezda and four more installed in Harmony. The American quarters are private, approximately person-sized soundproof booths. The Russian crew quarters include a small window, but do not provide the same amount of ventilation or block the same amount of noise as their American counterparts. A crewmember can sleep in a crew quarter in a tethered sleeping bag, listen to music, use a laptop, and store personal items in a large drawer or in nets attached to the module's walls. The module also provides a reading lamp, a shelf and a desktop. Visiting crews have no allocated sleep module, and attach a sleeping bag to an available space on a wall—it is possible to sleep floating freely through the station, but this is generally avoided because of the possibility of bumping into sensitive equipment. It is important that crew accommodations be well ventilated; otherwise, astronauts can wake up oxygen-deprived and gasping for air, because a bubble of their own exhaled carbon dioxide has formed around their heads.

Mission control centres

The components of the ISS are operated and monitored by their respective space agencies at control centres across the globe, including:
  • Roskosmos's Mission Control Center at Korolyov
    Korolyov (city)
    Korolyov or Korolev is an industrial city in Moscow Oblast, Russia, well known as the cradle of Soviet and Russian space exploration. It was originally founded as Kaliningrad in 1938 by Vasily Boldyrev, Naum Nosovsky, and Mikhail Loginov as the leading Soviet center for production of anti-tank...

    , Moscow Oblast, controls the Russian Orbital Segment
    Russian Orbital Segment
    The Russian Orbital Segment is the name given to the components of the International Space Station constructed in Russia and operated by the Russian Federal Space Agency...

     which handles Guidance, Navigation & Control for the entire Station., in addition to individual Soyuz and Progress missions.
  • ESA's ATV Control Centre, at the Toulouse Space Centre (CST) in Toulouse
    Toulouse
    Toulouse is a city in the Haute-Garonne department in southwestern FranceIt lies on the banks of the River Garonne, 590 km away from Paris and half-way between the Atlantic Ocean and the Mediterranean Sea...

    , France, controls flights of the unmanned European Automated Transfer Vehicle
    Automated Transfer Vehicle
    The Automated Transfer Vehicle or ATV is an expendable, unmanned resupply spacecraft developed by the European Space Agency . ATVs are designed to supply the International Space Station with propellant, water, air, payload and experiments...

    .
  • JAXA's JEM Control Centre and HTV Control Centre at Tsukuba Space Centre
    Tsukuba Space Center
    Tsukuba Space Center is the operations facility for the Japanese Space Agency located in Tsukuba Science City in Ibaraki Prefecture. The facility opened in 1972 and serves as the primary location for Japan's space operations and research programs...

     (TKSC) in Tsukuba, Japan, are responsible for operating the Japanese Experiment Module complex and all flights of the 'White Stork' HTV Cargo spacecraft, respectively.
  • NASA's Mission Control Center at Lyndon B. Johnson Space Center
    Lyndon B. Johnson Space Center
    The Lyndon B. Johnson Space Center is the National Aeronautics and Space Administration's center for human spaceflight training, research and flight control. The center consists of a complex of 100 buildings constructed on 1,620 acres in Houston, Texas, USA...

     in Houston, Texas, serves as the primary control facility for the United States segment of the ISS and also controls the Space Shuttle missions that visit the station.
  • NASA's Payload Operations and Integration Center
    Payload Operations and Integration Center
    Also known as Huntsville Operations Support Center or Payload Operations Center, it is a National Aeronautics and Space Administration facility that works in conjunction with the Space Station and Space Shuttle Control Centers in Houston, TX...

     at Marshall Space Flight Center
    Marshall Space Flight Center
    The George C. Marshall Space Flight Center is the U.S. government's civilian rocketry and spacecraft propulsion research center. The largest center of NASA, MSFC's first mission was developing the Saturn launch vehicles for the Apollo moon program...

     in Huntsville
    Huntsville, Alabama
    Huntsville is a city located primarily in Madison County in the central part of the far northern region of the U.S. state of Alabama. Huntsville is the county seat of Madison County. The city extends west into neighboring Limestone County. Huntsville's population was 180,105 as of the 2010 Census....

    , Alabama, coordinates payload operations in the USOS.
  • ESA's Columbus Control Centre
    Columbus Control Center
    The Columbus Control Centre is the Mission Control Center which is used to control the European Columbus research laboratory, which is part of the International Space Station . The control centre is located at the German Aerospace Center facility in Oberpfaffenhofen near Munich, Germany...

     at the German Aerospace Centre
    German Aerospace Center
    The German Aerospace Center is the national centre for aerospace, energy and transportation research of the Federal Republic of Germany. It has multiple locations throughout Germany. Its headquarters are located in Cologne. It is engaged in a wide range of research and development projects in...

     (DLR) in Oberpfaffenhofen
    Oberpfaffenhofen
    Oberpfaffenhofen is a village which is part of the municipality of Weßling in the district of Starnberg, Bavaria, Germany. It is 20 kilometers from the city center of Munich....

    , Germany, manages the European Columbus research laboratory.
  • CSA's MSS Control at Saint-Hubert
    Saint-Hubert, Quebec
    Saint-Hubert is a borough in the city of Longueuil, located in the Montérégie region of Quebec, Canada. It had been a separate city prior to January 1, 2002, when it along with several other neighbouring south shore municipalities were merged into Longueuil. According to the Quebec Statistics...

    , Quebec, Canada, controls and monitors the Mobile Servicing System
    Mobile Servicing System
    The Mobile Servicing System , better known by its primary component Canadarm2, is a robotic system and associated equipment on the International Space Station...

    , or Canadarm2.

Orbit

The ISS is maintained in a nearly circular orbit with a minimum mean altitude of 278 km (173 mi) and a maximum of 460 km (286 mi), in the centre of the Thermosphere
Thermosphere
The thermosphere is the biggest of all the layers of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. The International Space Station has a stable orbit within the middle of the thermosphere, between...

. It travels at an average speed of 27,724 kilometres (17,227 mi) per hour, and completes 15.7 orbits per day. The station's altitude was allowed to fall around the time of each NASA shuttle mission. Orbital boost burns would generally be delayed until after the shuttle's departure. This allowed shuttle payloads to be lifted with the station's engines during the routine firings, rather than have the shuttle lift itself and the payload together to a higher orbit. This trade-off allowed heavier loads to be transferred to the station. After the retirement of the NASA shuttle, the nominal orbit of the space station was raised in altitude. Other, more frequent supply ships don't require this adjustment as they are substantially lighter vehicles. Orbital boosting can be performed by the station's two main engines on the Zvezda service module, a Progress resupply vessel, or by ESA's ATV. It takes approximately two orbits (three hours) for the boost to a higher altitude to be completed.

In December 2008 NASA signed an agreement with the Ad Astra Rocket Company
Ad Astra Rocket Company
The Ad Astra Rocket Company is a rocket propulsion company dedicated to the development of advanced plasma rocket propulsion technology. Located in Webster, Texas, several miles from NASA's Johnson Space Center, the company was incorporated on January 14, 2005. The President and CEO of Ad Astra...

 which may result in the testing on the ISS of a VASIMR plasma propulsion engine. This technology could allow station-keeping to be done more economically than at present.

The Russian orbital segment handles Guidance, Navigation & Control for the entire Station. Initially, Zarya, the first module of the station, controlled the station until a short time after the Russian service module Zvezda docked and was transferred control. Zvezda contains the ESA built DMS-R Data Management System. Zvezda computes the station's position and orbital trajectory using redundant Earth horizon sensors, Sun and Solar horizon sensors, and star trackers. The USOS and ROS both have experimental position sensing equipment, which use the GPS
Global Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...

 and Russian GLONASS
GLONASS
GLONASS , acronym for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, is a radio-based satellite navigation system operated for the Russian government by the Russian Space Forces...

 systems. Amongst the problems with these experimental systems are the stations path and speed. GPS was not initially designed for orbital navigation and high speed (25,000 km/h). Once, during Expedition 10
Expedition 10
Expedition 10 was the 10th expedition to the International Space Station, using the Soyuz TMA-5, which stayed during the expedition for emergency evacuation.-Crew:-Mission parameters:*Perigee: 384 km...

, an incorrect command was sent to the station's computer, and the CMG system became 'saturated' (when the set of CMGs exceed their operational range or cannot track a series of rapid movements) Attitude control was automatically taken over by the Russian Attitude Control System thrusters for about one orbit, using about 14 kilograms of propellant before the fault was noticed and fixed. Thrusters are deactivated during EVAs for crew safety. When a space shuttle or Soyuz is docked to the station, it can also be used to maintain station attitude such as for troubleshooting. Shuttle control was used exclusively during installation
STS-117
- Crew Notes :The initial crew manifest before the Columbia accident was:Astronaut Mark Polansky was originally slated to pilot this mission, but was moved to STS-116, which he commanded...

 of the S3/S4 truss, which provides electrical power and data interfaces for the station's electronics.

Safety aspects

The space environment is hostile to life. Unprotected presence in space is characterised by an intense radiation field (consisting primarily of protons and other subatomic charged particles from the solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

, in addition to cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s), high vacuum, extreme temperatures, and microgravity. Some simple forms of life including Tardigrade
Tardigrade
Tardigrades form the phylum Tardigrada, part of the superphylum Ecdysozoa. They are microscopic, water-dwelling, segmented animals with eight legs. Tardigrades were first described by Johann August Ephraim Goeze in 1773...

s can survive in this environment in a desiccated state.

Radiation

The ISS is partially protected from the space environment by the Earth's magnetic field. From an average distance of about 70,000 km, depending on Solar activity, the magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

 begins to deflect solar wind around the Earth and ISS. However, solar flares
Coronal mass ejection
A coronal mass ejection is a massive burst of solar wind, other light isotope plasma, and magnetic fields rising above the solar corona or being released into space....

 are still a hazard to the crew, who may receive only a few minutes warning. The crew of Expedition 10
Expedition 10
Expedition 10 was the 10th expedition to the International Space Station, using the Soyuz TMA-5, which stayed during the expedition for emergency evacuation.-Crew:-Mission parameters:*Perigee: 384 km...

 took shelter as a precaution in 2005 in a more heavily shielded part of the ROS designed for this purpose during the initial 'proton storm' of an X-3 class solar flare.
Without the protection of the Earth's atmosphere, astronauts are exposed to higher levels of radiation
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...

 from a steady flux of cosmic ray
Cosmic ray
Cosmic rays are energetic charged subatomic particles, originating from outer space. They may produce secondary particles that penetrate the Earth's atmosphere and surface. The term ray is historical as cosmic rays were thought to be electromagnetic radiation...

s. Subatomic charged particles, primarily protons from solar wind
Solar wind
The solar wind is a stream of charged particles ejected from the upper atmosphere of the Sun. It mostly consists of electrons and protons with energies usually between 1.5 and 10 keV. The stream of particles varies in temperature and speed over time...

, penetrate living tissue and damage DNA. The station's crews are exposed to about 1 millisievert of radiation each day, which is about the same as someone would get in a year on Earth, from natural sources. This results in a higher risk of astronauts' developing cancer. High levels of radiation can cause damage to the chromosomes of lymphocytes. These cells are central to the immune system
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...

 and so any damage to them could contribute to the lowered immunity
Immunity (medical)
Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...

 experienced by astronauts. Over time lowered immunity results in the spread of infection between crew members, especially in such confined areas. Radiation has also been linked to a higher incidence of cataracts in astronauts. Protective shielding and protective drugs may lower the risks to an acceptable level, but data is scarce and longer-term exposure will result in greater risks.

Despite efforts to improve radiation shielding on the ISS compared to previous stations such as Mir, radiation levels within the station have not been vastly reduced, and it is thought that further technological advancement will be required to make long-duration human spaceflight further into the Solar System a possibility. Large, acute doses of radiation from Coronal Mass Ejection
Coronal mass ejection
A coronal mass ejection is a massive burst of solar wind, other light isotope plasma, and magnetic fields rising above the solar corona or being released into space....

 can cause radiation sickness and can be fatal. Without the protection of the Earth's magnetosphere
Magnetosphere
A magnetosphere is formed when a stream of charged particles, such as the solar wind, interacts with and is deflected by the intrinsic magnetic field of a planet or similar body. Earth is surrounded by a magnetosphere, as are the other planets with intrinsic magnetic fields: Mercury, Jupiter,...

, interplanetary manned missions are especially vulnerable.

The radiation levels experienced on ISS are about 5 times greater than those experienced by airline passengers and crew. The Earth's electromagnetic field provides almost the same level of protection against solar and other radiation in low Earth orbit as in the stratosphere. Airline passengers, however, experience this level of radiation for no more than 15 hours for the longest intercontinental flights. For example, on a 12 hour flight an airline passenger would experience 0.1 millisievert of radiation, or a rate of 0.2 millisieverts per day; only 1/5 the rate experienced by an astronaut in LEO.

Crew health

The most significant adverse effects of long-term weightlessness are muscle atrophy
Muscle atrophy
Muscle atrophy, or disuse atrophy, is defined as a decrease in the mass of the muscle; it can be a partial or complete wasting away of muscle. When a muscle atrophies, this leads to muscle weakness, since the ability to exert force is related to mass...

 and deterioration of the skeleton, or spaceflight osteopenia
Spaceflight osteopenia
Spaceflight osteopenia refers to the characteristic bone loss that occurs during spaceflight. Astronauts lose an average of more than 1% bone mass per month spent in space...

. Other significant effects include fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face. These effects begin to reverse quickly upon return to the Earth.

To prevent some of these adverse physiological effects, the station is equipped with two treadmills (including the COLBERT
Treadmill with Vibration Isolation System
The Treadmill with Vibration Isolation Stabilization System, commonly abbreviated as TVIS, is a treadmill for use on-board the International Space Station and is designed to allow astronauts to run without vibrating delicate microgravity science experiments in adjacent labs...

), the aRED (advanced Resistive Exercise Device) which enables various weightlifting exercises, and a stationary bicycle; each astronaut spends at least two hours per day exercising on the equipment. Astronauts use bungee cords to strap themselves to the treadmill. Researchers believe that exercise is a good countermeasure for the bone and muscle density loss that occurs when humans live for a long time without gravity.

Orbital debris

At the low altitudes at which the ISS orbits there is a variety of space debris, consisting of many different objects including entire spent rocket stages, dead satellites, explosion fragments—including materials from anti-satellite weapon
Anti-satellite weapon
Anti-satellite weapons are designed to incapacitate or destroy satellites for strategic military purposes. Currently, only the United States, the former Soviet Union, and the People's Republic of China are known to have developed these weapons. On September 13, 1985, the United States destroyed US...

 tests, paint flakes, slag from solid rocket motors, coolant released by RORSAT
RORSAT
Radar Ocean Reconnaissance SATellite or RORSAT is the western name given to the Soviet Upravlyaemyj Sputnik Aktivnyj satellites. These satellites were launched between 1967 and 1988 to monitor NATO and merchant vessels using active radar...

 nuclear powered satellites and some of the 750,000,000 small needles from the American military Project West Ford
Project West Ford
Project West Ford was a test carried out by Massachusetts Institute of Technology's Lincoln Laboratory on behalf of the United States Military in 1961 and 1963 to create an artificial ionosphere above the Earth...

. These objects, in addition to natural micrometeoroid
Micrometeoroid
A micrometeoroid is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram. A micrometeor or micrometeorite is such a particle that enters the Earth's atmosphere or falls to Earth.-Scientific interest:...

s, are a significant threat. Large objects can destroy the station, but are less of a threat as their orbits can be predicted. Objects too small to be detected by optical and radar instruments, from approximately 1cm down to microscopic size, number in the trillions. Despite their small size, some of these objects are a still a threat because of their kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

 and direction in relation to the station. Spacesuits of spacewalking crew could puncture, causing exposure to vacuum
Space exposure
Space exposure is the subjection of a human to the conditions of outer space, without protective clothing and beyond the Earth’s atmosphere in a vacuum.-Explanation and history:...

.
Space debris objects are tracked remotely from the ground, and the station crew can be notified. This allows for a Debris Avoidance Manoeuvre (DAM) to be conducted, which uses thrusters on the Russian Orbital Segment to alter the station's orbital altitude, avoiding the debris. DAMs are not uncommon, taking place if computational models show the debris will approach within a certain threat distance. Eight DAMs had been performed prior to March 2009, the first seven between October 1999 and May 2003. Usually the orbit is raised by one or two kilometres by means of an increase in orbital velocity of the order of 1 m/s. Unusually there was a lowering of 1.7 km on 27 August 2008, the first such lowering for 8 years. There were two DAMs in 2009, on 22 March and 17 July. If a threat from orbital debris is identified too late for a DAM to be safely conducted, the station crew close all the hatches aboard the station and retreat into their Soyuz spacecraft
Soyuz spacecraft
Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

, so that they would be able to evacuate in the event it was damaged by the debris. This partial station evacuation has occurred twice, on 13 March 2009 and 28 June 2011. Ballistic panels, also called micrometeorite shielding, is incorporated into the station to protect pressurized sections and critical systems. The type and thickness of these panels varies depending upon their predicted exposure to damage.

Repairs

Unexpected problems and failures have impacted the station's assembly time-line and work schedules leading to periods of reduced capabilities and, in some cases, could have forced abandonment of the station for safety reasons, had these problems not been resolved.

During STS-120
STS-120
-Crew notes:As commander of STS-120, Pamela Melroy became the second woman to command a space shuttle mission. Additionally, the Expedition 16 crew that received STS-120 was commanded by Peggy Whitson, the first female ISS commander...

 on 2007, following the relocation of the P6 truss and solar arrays, it was noted during the redeployment of the array that it had become torn and was not deploying properly. An EVA was carried out by Scott Parazynski
Scott E. Parazynski
Scott Edward Parazynski, M.D. is an American physician and a former NASA astronaut. A veteran of five Space Shuttle flights and seven spacewalks, Parazynski's latest mission was STS-120 in October, 2007 --- highlighted by a dramatic, unplanned EVA to repair a live solar array...

, assisted by Douglas Wheelock
Douglas H. Wheelock
Douglas Harry "Wheels" Wheelock is an American astronaut. He has flown in space twice logging 178 days on the Space Shuttle, International Space Station, and Russian Soyuz...

, the men took extra precautions to reduce the risk of electric shock, as the repairs were carried out with the solar array exposed to sunlight. The issues with the array were followed in the same year by problems with the starboard Solar Alpha Rotary Joint (SARJ), which rotates the arrays on the starboard side of the station. Excessive vibration and high-current spikes in the array drive motor were noted, resulting in a decision to substantially curtail motion of the starboard SARJ until the cause was understood. Inspections during EVAs on STS-120 and STS-123
STS-123
-Mission parameters:* Mass:* Orbiter liftoff: * Orbiter landing: * Perigee: 336 kilometers * Apogee: 346 kilometers * Inclination: 51.6 degrees* Period: 91.6min-Mission payloads:...

 showed extensive contamination from metallic shavings and debris in the large drive gear and confirmed damage to the large metallic race ring at the heart of the joint, and so the joint was locked to prevent further damage. Repairs to the joint were carried out during STS-126
STS-126
-Crew notes:Originally scheduled to fly on STS-126 was Joan E. Higginbotham, who was a mission specialist on STS-116. On 21 November 2007, NASA announced a change in the crew manifest due to Higginbotham's decision to leave NASA to take a job in the private sector. Stephen G...

 with lubrication of both joints and the replacement 11 of 12 trundle bearings on the joint.

In 2009, the engines on Zvezda were issued an incorrect command which caused resonant vibrations to propagate throughout the station structure which persisted for over two minutes. While no damage to the station was immediately reported, some components may have been stressed beyond their design limits. Further analysis confirmed that the station was unlikely to have suffered any structural damage, and it appears that "structures will still meet their normal lifetime capability". 2009 also saw damage to the S1 radiator, one of the components of the station's cooling system. The problem was first noticed in Soyuz
Soyuz spacecraft
Soyuz , Union) is a series of spacecraft initially designed for the Soviet space programme by the Korolyov Design Bureau in the 1960s, and still in service today...

 imagery in September 2008, but was not thought to be serious. The imagery showed that the surface of one sub-panel has peeled back from the underlying central structure, possibly due to micro-meteoroid or debris impact. It is also known that a Service Module thruster cover, jettisoned during an EVA in 2008, had struck the S1 radiator, but its effect, if any, has not been determined. On 15 May 2009 the damaged radiator panel's ammonia tubing was mechanically shut off from the rest of the cooling system by the computer-controlled closure of a valve. The same valve was used immediately afterwards to vent the ammonia from the damaged panel, eliminating the possibility of an ammonia leak from the cooling system via the damaged panel.

Early on 1 August 2010, a failure in cooling Loop A (starboard side), one of two external cooling loops, left the station with only half of its normal cooling capacity and zero redundancy in some systems. The problem appeared to be in the ammonia pump module that circulates the ammonia cooling fluid. Several subsystems, including two of the four CMGs, were shut down.

Planned operations on the ISS were interrupted through a series of EVAs to address the cooling system issue. A first EVA on 7 August 2010, to replace the failed pump module, was not fully completed due to an ammonia leak in one of four quick-disconnects. A second EVA on 11 August successfully removed the failed pump module. A third EVA was required to restore Loop A to normal functionality.

The USOS's cooling system is largely built by the American company Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...

, which is also the manufacturer of the failed pump.

An air leak from the USOS in 2004, the venting of fumes from an Elektron oxygen generator in 2006, and the failure of the computers in the ROS in 2007 during STS-117
STS-117
- Crew Notes :The initial crew manifest before the Columbia accident was:Astronaut Mark Polansky was originally slated to pilot this mission, but was moved to STS-116, which he commanded...

 which left the station without thruster,
Elektron, Vozdukh and other environmental control system operations, the root cause of which was found to be condensation inside the electrical connectors leading to a short-circuit.

Sightings

Before sunrise or after sunset, the ISS can appear to observers on the ground, with the naked eye
Naked eye
The naked eye is a figure of speech referring to human visual perception unaided by a magnifying or light-collecting optical device, such as a telescope or microscope. Vision corrected to normal acuity using corrective lenses is considered "naked"...

 as a slow moving, bright, white dot, slowly crossing the sky in 2 to 5 minutes. This happens when after sunset or before sunrise the ISS is still sunlit, which is typically the case up to a few hours after sunset or before sunrise. Because of its size, the ISS is the brightest man made object in the sky, with an approximate brightness of magnitude −4 when overhead, similar to Venus. The ISS can also produce flares
Satellite flare
Satellite flare is the phenomenon caused by the reflective surfaces on satellites reflecting sunlight directly onto the Earth below and appearing as a brief, bright "flare"....

 as sunlight glints off reflective surfaces as it orbits of up to 8 or 16 times the brightness of Venus. The ISS is also visible during broad daylight conditions, albeit with a great deal more effort.

Tools are provided by a number of websites such as Heavens-Above as well as smartphone
Smartphone
A smartphone is a high-end mobile phone built on a mobile computing platform, with more advanced computing ability and connectivity than a contemporary feature phone. The first smartphones were devices that mainly combined the functions of a personal digital assistant and a mobile phone or camera...

 applications that use the known orbital data
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...

 and the observer's longitude and latitude to predict when the ISS will be visible (weather permitting), where the station will appear to rise to the observer, the altitude above the horizon it will reach and the duration of the pass before the station disappears to the observer either by setting below the horizon or entering into Earth's shadow.

The ISS orbits at an inclination
Inclination
Inclination in general is the angle between a reference plane and another plane or axis of direction.-Orbits:The inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit...

 of 51.6 degrees to Earth's equator, necessary to ensure that Russian Soyuz and Progress spacecraft launched from the Baikonur Cosmodrome
Baikonur Cosmodrome
The Baikonur Cosmodrome , also called Tyuratam, is the world's first and largest operational space launch facility. It is located in the desert steppe of Kazakhstan, about east of the Aral Sea, north of the Syr Darya river, near Tyuratam railway station, at 90 meters above sea level...

 may be safely launched to reach the station. Spent rocket stages must be dropped into uninhabited areas and this limits the directions rockets can be launched from the spaceport. While this orbit makes the station visible from 95% of the inhabited land on Earth, it is not visible from extreme northern or southern latitudes.

International co-operation

International co-operation in space began in the early 1970's with the docking of Soyuz 19 and Apollo 18
Apollo 18
Apollo 18 may refer to:* One of the canceled Apollo missions of the American Apollo lunar program* The officially unnumbered Apollo spacecraft used in the Apollo–Soyuz Test Project* Apollo 18 , a 1992 album by They Might Be Giants...

, known in the US as the Apollo-Soyuz program
Apollo-Soyuz Test Project
-Backup crew:-Crew notes:Jack Swigert had originally been assigned as the command module pilot for the ASTP prime crew, but prior to the official announcement he was removed as punishment for his involvement in the Apollo 15 postage stamp scandal.-Soyuz crew:...

me, and in the USSR as the Soyuz-Apollo programme. From 1978–1987 the USSR's Interkosmos
Interkosmos
Interkosmos was a space program of the Soviet Union designed to include members of military forces of allied Warsaw Pact countries in manned and unmanned missions...

 programme included allied Warsaw Pact countries, and countries which were not Soviet allies, such as India, Syria and France, in manned and unmanned missions to Space stations Salyut 6 and 7. In 1986 the USSR extended this co-operation to a dozen countries in the MIR
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 programme. In 1994–98 NASA space shuttles and crew visited MIR in the Shuttle-Mir program
Shuttle-Mir Program
The Shuttle–Mir Program was a collaborative space program between Russia and the United States, which involved American Space Shuttles visiting the Russian space station Mir, Russian cosmonauts flying on the shuttle and an American astronaut flying aboard a Soyuz spacecraft to engage in...

me. In 1998 the ISS programme began.

Ownership of modules, station utilization by participant nations, and responsibilities for station resupply are established by the Space Station Intergovernmental Agreement (IGA). This international treaty was signed on 28 January 1998 by the primary nations involved in the Space Station project; the United States of America, Russia, Japan, Canada and eleven member states of the European Space Agency (Belgium, Denmark, France, Germany, Italy, The Netherlands, Norway, Spain, Sweden, Switzerland, and the United Kingdom). A second layer of agreements was then achieved, called Memoranda of Understanding (MOU), between NASA and ESA, CSA, RKA and JAXA. These agreements are then further split, such as for the contractual obligations between nations, and trading of partners' rights and obligations. Use of the Russian Orbital Segment is also negotiated at this level.

In addition to these main intergovernmental agreements, Brazil originally joined the programme as a bilateral partner of the United States by a contract with NASA to supply hardware. In return, NASA would provide Brazil with access to its ISS facilities on-orbit, as well as a flight opportunity for one Brazilian astronaut during the course of the ISS programme. However, due to cost issues, the subcontractor Embraer
Embraer
Embraer S.A. is a Brazilian aerospace conglomerate that produces commercial, military, and executive aircraft and provides aeronautical services....

 was unable to provide the promised ExPrESS pallet, and Brazil left the programme. Italy has a similar contract with NASA to provide comparable services, although Italy also takes part in the programme directly via its membership in ESA. The Chinese, who have their own space station programme in progress (Tiangong)
Project 921-2
Tiangong is a space station program of the People's Republic of China, with the goal of creating a third generation space station, comparable to MIR. This program is autonomous and unconnected to any other international space-active countries...

 have reportedly expressed interest in the project, especially if it would be able to work with the RKA
Russian Federal Space Agency
The Russian Federal Space Agency , commonly called Roscosmos and abbreviated as FKA and RKA , is the government agency responsible for the Russian space science program and general aerospace research. It was previously the Russian Aviation and Space Agency .Headquarters of Roscosmos are located...

. Chinese manned spacecraft and space stations have Russian compatible docking systems. However, China remains uninvolved. Expanding the partnership would require unanimous agreement of the existing partners. Chinese participation has been prevented by unilateral US opposition.
The heads of both the South Korean and Indian space agency ISRO announced at the first plenary session of the 2009 International Astronautical Congress
International Astronautical Congress
Every year, the International Astronautical Federation together with the International Academy of Astronautics and the International Institute of Space Law , holds the International Astronautical Congress which is hosted by one of the national society members of the IAF.They are an annual meeting...

 that their nations intend to join the ISS programme, with talks due to begin in 2010. The heads of agency also expressed support for extending ISS lifetime. European countries not part of the programme will be allowed access to the station in a three-year trial period, ESA officials say.

The Russian part of the station is operated and controlled by the Russian Federation's space agency and provides Russia with the right to nearly one-half of the crew time for the ISS. The allocation of remaining crew time (three to four crew members of the total permanent crew of six) and hardware within the other sections of the station is as follows: Columbus
Columbus (ISS module)
Columbus is a science laboratory that is part of the International Space Station and is the largest single contribution to the ISS made by the European Space Agency ....

: 51% for the ESA, 46.7% for NASA, and 2.3% for CSA.
Kibō
Japanese Experiment Module
The Japanese Experiment Module , also known with the nickname , is a Japanese science module for the International Space Station developed by JAXA. It is the largest single ISS module. The first two pieces of the module were launched on space shuttle missions STS-123 and STS-124...

: 51% for the JAXA, 46.7% for NASA, and 2.3% for CSA.
Destiny: 97.7% for NASA and 2.3% for CSA. Crew time, electrical power and rights to purchase supporting services (such as data upload and download and communications) are divided 76.6% for NASA, 12.8% for JAXA, 8.3% for ESA, and 2.3% for CSA.

Cost

RSA costs are difficult to determine as substantial development costs of the Progress spacecraft, Soyuz spacecraft and Proton rockets used for module launches, are spread across previous Soviet rocket programmes. Cost of development for module design such as DOS base blocks, life support and docking systems are spread across the budgets of the Salyut, Almaz
Almaz
The Almaz program was a series of military space stations launched by the Soviet Union under cover of the civilian Salyut DOS-17K program after 1971....

, and Mir
Mir
Mir was a space station operated in low Earth orbit from 1986 to 2001, at first by the Soviet Union and then by Russia. Assembled in orbit from 1986 to 1996, Mir was the first modular space station and had a greater mass than that of any previous spacecraft, holding the record for the...

 1 and 2 programmes. Russian Prime Minister Vladimir Putin stated in January 2011 that the government will spend 115 billion rubles (US$3.8 billion) on national space programmes in 2011, however this includes the entire space programme which will launch a spacecraft on average once per week during 2011.

Criticism

The International Space Station has been the target of varied criticism over the years. Critics contend that the time and money spent on the ISS could be better spent on other projects—whether they be robotic spacecraft
Robotic spacecraft
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...

 missions, space exploration
Space exploration
Space exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....

, investigations of problems here on Earth, or just tax savings. Some critics, like Robert L. Park
Robert L. Park
Robert Lee Park , also known as Bob Park, is an emeritus professor of physics at the University of Maryland, College Park and a former Director of Public Information at the Washington office of the American Physical Society...

, argue that very little scientific
Scientific method
Scientific method refers to a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed scientific, a method of inquiry must be based on gathering empirical and measurable evidence subject to specific principles of...

 research
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...

 was convincingly planned for the ISS in the first place. They also argue that the primary feature of a space-based laboratory is its microgravity environment
Microgravity environment
The term micro-g environment is more or less a synonym of weightlessness and zero-G, but indicates that g-forces are not quite zero, just very small...

, which can usually be studied more cheaply with a "vomit comet
Vomit Comet
A Reduced Gravity Aircraft is a type of fixed-wing aircraft that briefly provides a nearly weightless environment in which to train astronauts, conduct research and film motion pictures....

".

The research done on the ISS is generally limited to experiments which do not require any specialized apparatus. For example, in the first half of 2007, ISS research dealt primarily with human biological responses to being in space, covering topics like kidney stones, circadian rhythm
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...

, and the effects of cosmic rays on the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...

.

Other critics have attacked the ISS on some technical design grounds:
  1. Jeff Foust
    Jeff Foust
    Dr Jeff Foust is an aerospace analyst, journalist and publisher. He is the editor and publisher of The Space Review and has written for Astronomy Now and The New Atlantis....

     argued that the ISS requires too much maintenance, especially by risky, expensive EVAs
    Extra-vehicular activity
    Extra-vehicular activity is work done by an astronaut away from the Earth, and outside of a spacecraft. The term most commonly applies to an EVA made outside a craft orbiting Earth , but also applies to an EVA made on the surface of the Moon...

    . The magazine The American Enterprise reports, for instance, that ISS astronauts "now spend 85 percent of their time on construction and maintenance" alone.
  2. The Astronomical Society of the Pacific has mentioned that its orbit is rather highly inclined, which makes Russian launches cheaper, but US launches more expensive. This was intended as a design point, to encourage Russian involvement with the ISS—and Russian involvement saved the project from abandonment in the wake of the Space Shuttle Columbia disaster
    Space Shuttle Columbia disaster
    The Space Shuttle Columbia disaster occurred on February 1, 2003, when shortly before it was scheduled to conclude its 28th mission, STS-107, the Space Shuttle Columbia disintegrated over Texas and Louisiana during re-entry into the Earth's atmosphere, resulting in the death of all seven crew members...

    —but the choice may have increased the costs of completing the ISS substantially.


A review of the claims by the Federation of American Scientists argued that NASA's rate of return from spin-offs is actually "astoundingly bad", except for aeronautics work that has led to aircraft sales.

Critics also say that NASA is often casually credited with "spin-offs" (such as Velcro
Velcro
Velcro is the brand name of the first commercially marketed fabric hook-and-loop fastener, invented in 1948 by the Swiss electrical engineer George de Mestral...

 and portable computers) that were developed independently for other reasons. NASA maintains a list of spin-offs from the construction of the ISS, as well as from work performed on the ISS. However, NASA's official list is much narrower and more arcane than dramatic narratives of billions of dollars of spin-offs. It is therefore debatable whether the ISS, as distinct from the wider space program, will be a major contributor to society.

End of mission

According to a 2009 report, RKK Energia is considering methods to remove from the station some modules of the Russian Orbital Segment when the end of mission is reached and use them as a basis for a new station, known as the Orbital Piloted Assembly and Experiment Complex
Orbital Piloted Assembly and Experiment Complex
The Orbital Piloted Assembly and Experiment Complex ' is the planned Russian successor to the International Space Station, with the main goal of supporting deep space exploration.-Overview:...

 (OPSEK). The modules under consideration for removal from the current ISS include the Multipurpose Laboratory Module
Multipurpose Laboratory Module
Nauka , also known as the Multipurpose Laboratory Module , , will be a component of the International Space Station , funded by the Russian Federal Space Agency. In the original ISS plans, Nauka was to use the location of the Docking and Stowage Module...

 (MLM), currently scheduled to be launched in May 2012, with other Russian modules which are currently planned to be attached to the MLM until 2015. Neither the MLM nor any additional modules attached to it would have reached the end of their useful lives in 2016 or 2020. The report presents a statement from an unnamed Russian engineer who believes that, based on the experience from Mir, a thirty-year life should be possible, except for micrometeorite damage, because the Russian modules have been built with on-orbit refurbishment in mind.

According to the Outer Space Treaty
Outer Space Treaty
The Outer Space Treaty, formally the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies, is a treaty that forms the basis of international space law...

 the United States is legally responsible for all modules it has launched. In ISS planning, NASA examined options including returning the station to Earth via shuttle missions (deemed too expensive, as the station (USOS) is not designed for disassembly and this would require at least 27 shuttle missions), natural orbital decay with random reentry similar to Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, boosting the station to a higher altitude (which would simply delay reentry) and a controlled targeted de-orbit to a remote ocean area.

The technical feasibility of a controlled targeted deorbit into a remote ocean was found to be possible only with Russia's assistance. At the time ISS was launched, the Russian Space Agency had experience from de-orbiting the Salyut 4
Salyut 4
Salyut 4 was a Salyut space station launched on December 26, 1974 into an orbit with an apogee of 355 km, a perigee of 343 km and an orbital inclination of 51.6 degrees. It was essentially a copy of the DOS 3, and unlike its ill-fated sibling it was a complete success...

, 5
Salyut 5
Salyut 5 , also known as OPS-3, was a Soviet space station. Launched in 1976 as part of the Salyut programme, it was the third and last Almaz space station to be launched for the Soviet military. Two Soyuz missions visited the station, each manned by two cosmonauts...

, 6
Salyut 6
Salyut 6 , DOS-5, was a Soviet orbital space station, the eighth flown as part of the Salyut programme. Launched on 29 September 1977 by a Proton rocket, the station was the first of the 'second-generation' type of space station. Salyut 6 possessed several revolutionary advances over the earlier...

, and 7
Salyut 7
Salyut 7 was a space station in low Earth orbit from April 1982 to February 1991. It was first manned in May 1982 with two crew via Soyuz T-5, and last visited in June 1986, by Soyuz T-15. Various crew and modules were used over its lifetime, including a total of 12 manned and 15 unmanned launches...

 space stations, while NASA's first intentional controlled de-orbit of a satellite (the Compton Gamma Ray Observatory
Compton Gamma Ray Observatory
The Compton Gamma Ray Observatory was a space observatory detecting light from 20 KeV to 30 GeV in Earth orbit from 1991 to 2000. It featured four main telescopes in one spacecraft covering x-rays and gamma-rays, including various specialized sub-instruments and detectors...

) would not occur for another two years. NASA currently has no spacecraft capable of de-orbiting the ISS at the time of decommissioning. Skylab
Skylab
Skylab was a space station launched and operated by NASA, the space agency of the United States. Skylab orbited the Earth from 1973 to 1979, and included a workshop, a solar observatory, and other systems. It was launched unmanned by a modified Saturn V rocket, with a mass of...

, the only space station built and launched entirely by the US, decayed from orbit slowly over 5 years, and no attempt was made to de-orbit the station using a deorbital burn. Remains of Skylab hit populated areas of Esperance, Western Australia
Esperance, Western Australia
Esperance is a large town in the Goldfields-Esperance region of Western Australia, located on the Southern Ocean coastline approximately east-southeast of the state capital, Perth. The shire of Esperance is home to 9,536 people as of the 2006 census, its major industries are tourism, agriculture,...

. without injuries or loss of life.

While the entire USOS cannot be reused and will be discarded, some Russian modules will be reused. Nauka, the Node module
Node Module
The Node Module is a pressurized module of the Russian Segment of the International Space Station and will be used in the OPSEK space station...

, two science power platforms and Rassvet, launched between 2010 and 2015 and joined to the ROS will be separated to form the next Russian space station OPSEK.

External links

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