Mars Climate Orbiter
Overview
 
The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was a 338 kilogram (750 lb
LB
-Codes:*.lb, the Internet country code top-level domain for Lebanon*Labrador's former postal abbreviation*Lloyd Aéreo Boliviano airline's IATA code*Luxembourgish language's ISO 639 alpha-2 code*Lebanon's ISO 3166-1 alpha-2 country code...

) robotic
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...

 space probe
Space probe
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...

 launched by 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...

 on December 11, 1998 to study the Martian climate
Climate of Mars
The climate of Mars has been an issue of scientific curiosity for centuries, not least because Mars is the only terrestrial planet whose surface can be directly observed in detail from the Earth....

, atmosphere, surface changes
Martian Surface
The study of surface characteristics is a broad category of Mars science that examines the nature of the materials making up the Martian surface. The study evolved from telescopic and remote-sensing techniques developed by astronomers to study planetary surfaces...

 and to act as the communications relay in the Mars Surveyor '98 program
Mars Surveyor '98 program
The Mars Surveyor '98 program comprised two spacecraft launched separately, the Mars Climate Orbiter and the Mars Polar Lander ; on board the Mars Polar Lander spacecraft were two surface-penetrator probes...

, for Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

. However, on September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to a navigational error.
Encyclopedia
The Mars Climate Orbiter (formerly the Mars Surveyor '98 Orbiter) was a 338 kilogram (750 lb
LB
-Codes:*.lb, the Internet country code top-level domain for Lebanon*Labrador's former postal abbreviation*Lloyd Aéreo Boliviano airline's IATA code*Luxembourgish language's ISO 639 alpha-2 code*Lebanon's ISO 3166-1 alpha-2 country code...

) robotic
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...

 space probe
Space probe
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...

 launched by 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...

 on December 11, 1998 to study the Martian climate
Climate of Mars
The climate of Mars has been an issue of scientific curiosity for centuries, not least because Mars is the only terrestrial planet whose surface can be directly observed in detail from the Earth....

, atmosphere, surface changes
Martian Surface
The study of surface characteristics is a broad category of Mars science that examines the nature of the materials making up the Martian surface. The study evolved from telescopic and remote-sensing techniques developed by astronomers to study planetary surfaces...

 and to act as the communications relay in the Mars Surveyor '98 program
Mars Surveyor '98 program
The Mars Surveyor '98 program comprised two spacecraft launched separately, the Mars Climate Orbiter and the Mars Polar Lander ; on board the Mars Polar Lander spacecraft were two surface-penetrator probes...

, for Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

. However, on September 23, 1999, communication with the spacecraft was lost as the spacecraft went into orbital insertion, due to a navigational error. The spacecraft encountered Mars at an improperly low altitude, causing it to incorrectly enter the upper atmosphere and disintegrate.

History

After the loss of Mars Observer
Mars Observer
The Mars Observer spacecraft, also known as the Mars Geoscience/Climatology Orbiter, was a 1,018-kilogram robotic space probe launched by NASA on September 25, 1992 to study the Martian surface, atmosphere, climate and magnetic field...

 and the onset of the rising costs associated with the future International Space Station
International Space Station
The International Space Station is a habitable, artificial satellite in low Earth orbit. The ISS follows the Salyut, Almaz, Cosmos, Skylab, and Mir space stations, as the 11th space station launched, not including the Genesis I and II prototypes...

, 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...

 began seeking cheaper, smaller solutions to scientific interplanetary missions. In 1994, the Panel on Small Spacecraft Technology was established to set guidelines for future miniature spacecraft. The panel determined that the new line of miniature spacecraft should be under 1000 kilograms with highly focused instrumentation. In 1995, a new Mars Surveyor program began as a set of missions designed with limited objectives, low costs, and frequent launches. The first mission in the new program was Mars Global Surveyor
Mars Global Surveyor
The Mars Global Surveyor was a US spacecraft developed by NASA's Jet Propulsion Laboratory and launched November 1996. It began the United States's return to Mars after a 10-year absence. It completed its primary mission in January 2001 and was in its third extended mission phase when, on 2...

, launched in 1996 to map Mars and provide geologic data using instruments intended for Mars Observer. Following Mars Global Surveyor, Mars Climate Orbiter carried two instruments, one originally intended for Mars Observer, to study the climate and weather of Mars.

The primary science objectives of the mission included:
  • determine the distribution of water on Mars
  • monitor the daily weather and atmospheric conditions
  • record changes on the martian surface due to wind and other atmospheric effects
  • determine temperature profiles of the atmosphere
  • monitor the water vapor and dust content of the atmosphere
  • look for evidence of past climate change.

Spacecraft design

The Mars Climate Orbiter bus measured 2.1 meters tall, 1.6 meters wide and 2 meters deep. The internal structure is largely constructed with graphite composite/aluminum honeycomb supports, a design found in many commercial airplanes. With exception to the scientific instruments, battery and main engine, the spacecraft includes dual redundancy on the most important systems.

The spacecraft was 3-axis stabilized and included eight, hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 monopropellant
Monopropellant rocket
A monopropellant rocket is a rocket that uses a single chemical as its propellant.-Chemical-reaction monopropellant rockets:...

 thrusters (four 22N thrusters to perform trajectory corrections; four 0.9N thrusters to control attitude). Orientation of the spacecraft was determined with a star tracker, two Sun sensors and two inertial measurement units. Orientation was controlled by firing the thrusters or using three reaction wheels. To perform the Mars orbital insertion maneuver, the spacecraft also included a LEROS 1B main engine rocket, providing 640N of thrust by burning hydrazine
Hydrazine
Hydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...

 fuel with nitrogen tetroxide (NTO) oxidizer.

The spacecraft included a 1.3 meter high-gain antenna
High-gain antenna
A high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...

 to transceive data with the Deep Space Network
Deep Space Network
The Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...

 over the x-band. The radio transponder designed for the Cassini–Huygens mission was used as a cost saving measure. The orbiter also included a two-way UHF radio frequency system to relay communications with Mars Polar Lander
Mars Polar Lander
The Mars Polar Lander, also referred to as the Mars Surveyor '98 Lander, was a 290-kilogram robotic spacecraft lander, launched by NASA on January 3, 1999, to study the soil and climate of Planum Australe, a region near the south pole on Mars, as part of the Mars Surveyor '98 mission...

 upon an expected landing on December 3, 1999.

The space probe was powered with a 3-panel solar array, providing an average of 500 W at Mars. Deployed, the solar array measures 5.5 meters in length. Power is stored in 12-cell, 16-amp-hour 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...

. The batteries were intended to be recharged when the solar array received sunlight and power the spacecraft as it passed into the shadow of Mars. When entering into orbit around Mars, the solar array was to be utilized in the aerobraking
Aerobraking
Aerobraking is a spaceflight maneuver that reduces the high point of an elliptical orbit by flying the vehicle through the atmosphere at the low point of the orbit . The resulting drag slows the spacecraft...

 maneuver, to slow the spacecraft until a circular orbit was achieved. The design is largely adapted from guidelines from the Small Spacecraft Technology Initiative outlined in the book, Technology for Small Spacecraft.

In an effort to simplify previous implementations of computers on spacecraft, Mars Climate Orbiter featured a single computer using an IBM RAD6000
RAD6000
The RAD6000 radiation-hardened single board computer, based on the IBM RISC Single Chip CPU, was manufactured by IBM Federal Systems. IBM Federal Systems was sold to Loral, and by way of acquisition, ended up with Lockheed Martin and is currently a part of BAE Systems...

 processor capable of 5MHz, 10MHz and 20MHz operations. Data storage is maintained on 128MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

 of random-access memory
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...

 (RAM) and 18MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

 of flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...

. The flash memory was intended to be used for highly important data, including triplicate copies of the flight system software.

The cost of the mission was $327.6 million total for both orbiter and lander, $193.1 million for spacecraft development, $91.7 million for launching it, and $42.8 million for mission operations.

Scientific instruments

Pressure Modulated Infrared Radiometer (PMIRR)
EWLINE
Utilizes narrow-band radiometric channels and two pressure modulation cells to measure atmospheric and surface emissions in the thermal infrared and a visible channel to measure dust particles and condensates in the atmosphere and on the surface at varying longitudes and seasons.
  • Principal investigator: Daniel McCleese / JPL/CALTECH
  • similar objectives achieved with Mars Climate Sounder on board Mars Reconnaissance Orbiter
    Mars Reconnaissance Orbiter
    Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...


----
Mars Color Imager (MARCI)

-see diagram
EWLINE
EWLINE
EWLINE Wide Angle Camera Filters
Filter Name Wavelength Sensitivity

The Mars Color Imager is a two-camera (medium-angle/wide-angle) imaging system designed to obtain pictures of the martian surface and atmosphere. Under proper conditions, resolutions up to 1 kilometer (0.5 miles) are possible.
  • Principal investigator: Michael Malin / Malin Space Science Systems (website)
  • reincorporated on Mars Reconnaissance Orbiter
    Mars Reconnaissance Orbiter
    Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...


----

Mission profile

Timeline of travel
Date Event
Spacecraft launched at 18:45:51 UTC
Mars orbital insertion maneuver.
= Events that are unaccounted for but planned for the mission.
Communication with spacecraft lost at 09:04:52 UTC.
Mission declared a loss. No further attempts to contact.

Launch and trajectory

The Mars Climate Orbiter probe was launched on December 11, 1998 at 18:45:51 UTC by the National Aeronautics and Space Administration from Space Launch Complex 17A at the Cape Canaveral Air Force Station
Cape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...

 in Florida, aboard a Delta II 7425
Delta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...

 launch vehicle. The complete burn sequence lasted 42 minutes bringing the spacecraft into a Hohmann transfer orbit
Hohmann transfer orbit
In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane....

, with a final velocity of 5.5 km/s relative to Mars, and sending the probe into a 669 million kilometer trajectory. At launch, Mars Climate Orbiter weighed 638 kilograms (1,418 pounds) including propellant.

Encounter with Mars

Mars Climate Orbiter began the planned orbital insertion maneuver on September 23, 1999 at 09:00:46 UTC. However, due to complications arisen from human error, the spacecraft encountered Mars at a lower than anticipated altitude and disintegrated due to atmospheric stresses. Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter
Mars Reconnaissance Orbiter is a NASA multipurpose spacecraft designed to conduct reconnaissance and Exploration of Mars from orbit...

has since completed most of the intended objectives for this mission.

Communications loss

On September 23, 1999, during the Mars orbital insertion maneuver, Mars Climate Orbiter went out of radio contact when the spacecraft passed behind Mars at 09:04:52 UTC, 49 seconds earlier than expected, and communication was never reestablished.

On November 10, 1999, the Mars Climate Orbiter Mishap Investigation Board released a Phase I report, detailing the suspected issues encountered with the loss of the spacecraft. Previously, on September 8, 1999, Trajectory Correction Maneuver-4 was computed and then executed on September 15, 1999. It was intended to place the spacecraft at an optimal position for an orbital insertion maneuver that would bring the spacecraft around Mars at an altitude of 226 kilometers on September 23, 1999. However, during the week between TCM-4 and the orbital insertion maneuver, the navigation team indicated the altitude may be much lower than intended at 150 to 170 kilometers. Twenty-four hours prior to orbital insertion, calculations placed the orbiter at an altitude of 110 kilometers; 80 kilometers is the minimum altitude that Mars Climate Orbiter was thought to be capable of surviving during this maneuver. Final calculations placed the spacecraft in a trajectory that would have taken the orbiter within 57 kilometers of the surface where the spacecraft likely disintegrated because of atmospheric stresses. The primary cause of this discrepancy was human error. Specifically, the flight system software on the Mars Climate Orbiter was written to calculate thruster performance using the metric unit Newtons (N), while the ground crew was entering course correction and thruster data using the Imperial measure Pound-force
Pound-force
The pound force is a unit of force in some systems of measurement including English engineering units and British gravitational units.- Definitions :...

 (lbf). This error has since been known as the metric mixup and has been carefully avoided in all missions since by 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...

.

See also

  • Metrication
    Metrication
    Metrication refers to the introduction and use of the SI metric system, the international standard for physical measurements. This has involved a long process of independent and systematic conversions of countries from various local systems of weights and measures. Metrication began in France in...

  • 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....

  • Unmanned space mission
  • Gimli Glider
    Gimli Glider
    The Gimli Glider is the nickname of the Air Canada aircraft that was involved in a notable aviation incident. On 23 July 1983, Air Canada Flight 143, a Boeing 767-200 jet, ran out of fuel at an altitude of ASL, about halfway through its flight from Montreal to Edmonton via Ottawa...

    , an aircraft involved in an incident after poor metrication caused it to run out of fuel

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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