Interstellar Boundary Explorer
Encyclopedia
Interstellar Boundary Explorer (IBEX) is a NASA
satellite that will make the first map of the boundary between the Solar System
and interstellar space. The mission is part of NASA's Small Explorer program
. The IBEX satellite was launched with a Pegasus-XL rocket on October 19, 2008, at 17:47:23 UTC
. The nominal mission baseline duration will be two years to observe the entire solar system boundary.
The design and operation of the mission is being led by the Southwest Research Institute
, with the Los Alamos National Laboratory
and the Lockheed Martin
Advanced Technology Center serving as co-investigator institutions responsible for the IBEX-Hi and IBEX-Lo sensors respectively. The Orbital Sciences Corporation
manufactured the spacecraft bus and was the location for spacecraft environmental testing.
IBEX is in a sun-oriented spin-stabilized orbit around the Earth.
will be imaged by measuring the location and magnitude of charge-exchange collisions occurring in all directions. This will ultimately yield a map of the termination shock of the solar wind
. The satellite's payload consists of two energetic neutral atom
(ENA) imagers, IBEX-Hi and IBEX-Lo. Each of these sensors consists of a collimator
that limits their fields-of-view, a conversion surface to convert neutral hydrogen
and oxygen
into ions, an electrostatic analyzer
(ESA) to suppress ultraviolet
light and to select ions of a specific energy range, and a detector to count particles and identify the type of each ion. The IBEX-Hi instrument will record particle counts in a higher energy band than the IBEX-Lo does. The scientific payload also includes a Combined Electronics Unit (CEU) that controls the voltages on the collimator and the ESA, and it will read and record data from the particle detectors of each sensor.
The IBEX satellite, initially launched into a highly-elliptical transfer orbit with a low perigee, used a solid fuel rocket motor as its final boost stage at apogee, in order to raise its perigee greatly and to achieve its desired high-altitude elliptical orbit.
The IBEX is in a highly-eccentric elliptical terrestrial orbit, which ranges from a perigee
of about 8000 kilometres (4,971 mi) to an apogee of about 300000 kilometres (186,411.8 mi), that is, about three-quarters of the distance to the Moon
. (These orbital numbers vary somewhat due to accumulated atmospheric drag around perigees, and because of gravitational perturbations from the Moon and other astronomical bodies.) This very high orbit allows the IBEX satellite to move out of the Earth's magnetosphere
(the Van Allen Belts) when making scientific observations. This extreme altitude is critical due to the amount of charged-particle interference that would occur while taking images while within the radiation belts. When within the magnetosphere of the Earth (70000 kilometres (43,496.1 mi)), the satellite will perform other functions, including telemetry
downlinks.
The IBEX satellite was carried into outer space October 19, 2008, by a Pegasus XL rocket. The Pegasus rocket was released from a Lockheed L-1011
Stargazer
airplane that took off from Kwajalein Atoll in the Central Pacific Ocean
. The air-drop occurred at 17:47:23 UTC
. By launching from this site close to the Equator
, the Pegasus rocket lifted as much as 35 pounds (15.9 kg) more mass to orbit than it would have with a launch from the Kennedy Space Center
in Florida
.
The IBEX was mated to its Pegasus XL rocket at Vandenberg Air Force Base
, California
, and the combined vehicle was then suspended below the Stargazer
mother airplane, and flown to Kwajalein, a several-hours-long flight. The L-1011 arrived at Kwajalein Atoll on Sunday, October 12, 2008.
(ENA) emissions that are traveling through the solar system to Earth that cannot be measured by conventional telescopes. These ENAs are created on the boundary of our Solar System by the interactions between solar wind
particles and interstellar medium particles.
ribbon, but everyone agrees that it means the textbook picture of the heliosphere
—in which the solar system's enveloping pocket filled with the solar wind's charged particles is plowing through the onrushing 'galactic wind' of the interstellar medium in the shape of a comet—is wrong". The Sun is currently traveling through the Local Interstellar Cloud
, and the heliosphere's size and shape are key factors in determining its shielding power from cosmic ray
s. Should IBEX detect changes in the shape of the ribbon, that could show how the heliosphere is interacting with the Local Fluff
.
In October 2010, significant changes were detected in the ribbon after 6 months, based on the second set of IBEX observations.
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...
satellite that will make the first map of the boundary between the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
and interstellar space. The mission is part of NASA's Small Explorer program
Small Explorer program
The Small Explorer program is an effort within NASA to fund space exploration missions that cost no more than $120 million.- Program history :...
. The IBEX satellite was launched with a Pegasus-XL rocket on October 19, 2008, at 17:47:23 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
. The nominal mission baseline duration will be two years to observe the entire solar system boundary.
The design and operation of the mission is being led by the Southwest Research Institute
Southwest Research Institute
Southwest Research Institute , headquartered in San Antonio, Texas, is one of the oldest and largest independent, nonprofit, applied research and development organizations in the United States...
, with the Los Alamos National Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...
and the Lockheed Martin
Lockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
Advanced Technology Center serving as co-investigator institutions responsible for the IBEX-Hi and IBEX-Lo sensors respectively. The Orbital Sciences Corporation
Orbital Sciences Corporation
Orbital Sciences Corporation is an American company which specializes in the manufacturing and launch of satellites. Its Launch Systems Group is heavily involved with missile defense launch systems...
manufactured the spacecraft bus and was the location for spacecraft environmental testing.
IBEX is in a sun-oriented spin-stabilized orbit around the Earth.
Payload
The heliospheric boundary of the Solar SystemSolar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
will be imaged by measuring the location and magnitude of charge-exchange collisions occurring in all directions. This will ultimately yield a map of the termination shock of 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...
. The satellite's payload consists of two energetic neutral atom
Energetic neutral atom
Energetic neutral atom imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and at the boundary of the heliosphere - the far flung outer edge of the solar system.ENA images are constructed...
(ENA) imagers, IBEX-Hi and IBEX-Lo. Each of these sensors consists of a collimator
Collimator
A collimator is a device that narrows a beam of particles or waves. To "narrow" can mean either to cause the directions of motion to become more aligned in a specific direction or to cause the spatial cross section of the beam to become smaller.- Optical collimators :In optics, a collimator may...
that limits their fields-of-view, a conversion surface to convert neutral hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
into ions, an electrostatic analyzer
Electrostatic analyzer
An electrostatic analyzer or ESA is an instrument used in ion optics that employs an electric field to allow the passage of only those ions or electrons that have a given specific energy. It usually also focuses these particles into a smaller area...
(ESA) to suppress ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light and to select ions of a specific energy range, and a detector to count particles and identify the type of each ion. The IBEX-Hi instrument will record particle counts in a higher energy band than the IBEX-Lo does. The scientific payload also includes a Combined Electronics Unit (CEU) that controls the voltages on the collimator and the ESA, and it will read and record data from the particle detectors of each sensor.
Mission parameters
The IBEX is in a highly-eccentric elliptical terrestrial orbit, which ranges from a perigee
Perigee
Perigee is the point at which an object makes its closest approach to the Earth.. Often the term is used in a broader sense to define the point in an orbit where the orbiting body is closest to the body it orbits. The opposite is the apogee, the farthest or highest point.The Greek prefix "peri"...
of about 8000 kilometres (4,971 mi) to an apogee of about 300000 kilometres (186,411.8 mi), that is, about three-quarters of the distance to the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
. (These orbital numbers vary somewhat due to accumulated atmospheric drag around perigees, and because of gravitational perturbations from the Moon and other astronomical bodies.) This very high orbit allows the IBEX satellite to move out 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,...
(the Van Allen Belts) when making scientific observations. This extreme altitude is critical due to the amount of charged-particle interference that would occur while taking images while within the radiation belts. When within the magnetosphere of the Earth (70000 kilometres (43,496.1 mi)), the satellite will perform other functions, including 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...
downlinks.
Launch
Lockheed L-1011
The Lockheed L-1011 TriStar, commonly referred to as the L-1011 or TriStar, is a medium-to-long range, widebody passenger trijet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed...
Stargazer
Stargazer (aircraft)
Stargazer, registration number N140SC, is a modified Lockheed L-1011 TriStar aircraft used by Orbital Sciences Corporation as a mother ship launch pad for Pegasus rockets...
airplane that took off from Kwajalein Atoll in the Central Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The air-drop occurred at 17:47:23 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
. By launching from this site close to the Equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, the Pegasus rocket lifted as much as 35 pounds (15.9 kg) more mass to orbit than it would have with a launch from the Kennedy Space Center
Kennedy Space Center
The John F. Kennedy Space Center is the NASA installation that has been the launch site for every United States human space flight since 1968. Although such flights are currently on hiatus, KSC continues to manage and operate unmanned rocket launch facilities for America's civilian space program...
in Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
.
The IBEX was mated to its Pegasus XL rocket at Vandenberg Air Force Base
Vandenberg Air Force Base
Vandenberg Air Force Base is a United States Air Force Base, located approximately northwest of Lompoc, California. It is under the jurisdiction of the 30th Space Wing, Air Force Space Command ....
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, and the combined vehicle was then suspended below the Stargazer
Stargazer (aircraft)
Stargazer, registration number N140SC, is a modified Lockheed L-1011 TriStar aircraft used by Orbital Sciences Corporation as a mother ship launch pad for Pegasus rockets...
mother airplane, and flown to Kwajalein, a several-hours-long flight. The L-1011 arrived at Kwajalein Atoll on Sunday, October 12, 2008.
Data collection
IBEX is collecting Energetic neutral atomEnergetic neutral atom
Energetic neutral atom imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and at the boundary of the heliosphere - the far flung outer edge of the solar system.ENA images are constructed...
(ENA) emissions that are traveling through the solar system to Earth that cannot be measured by conventional telescopes. These ENAs are created on the boundary of our Solar System by the interactions between 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...
particles and interstellar medium particles.
Astronomical results
Initial data revealed a previously unpredicted "very narrow ribbon that is two to three times brighter than anything else in the sky". Initial interpretations suggest that "the interstellar environment has far more influence on structuring the heliosphere than anyone previously believed". "No one knows what is creating the ENA (energetic neutral atoms)Energetic neutral atom
Energetic neutral atom imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and at the boundary of the heliosphere - the far flung outer edge of the solar system.ENA images are constructed...
ribbon, but everyone agrees that it means the textbook picture of the heliosphere
Heliosphere
The heliosphere is a bubble in space "blown" into the interstellar medium by the solar wind. Although electrically neutral atoms from interstellar volume can penetrate this bubble, virtually all of the material in the heliosphere emanates from the Sun itself...
—in which the solar system's enveloping pocket filled with the solar wind's charged particles is plowing through the onrushing 'galactic wind' of the interstellar medium in the shape of a comet—is wrong". The Sun is currently traveling through the Local Interstellar Cloud
Local Interstellar Cloud
The Local Interstellar Cloud is the interstellar cloud roughly 30 light years across through which the Earth's solar system is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain...
, and the heliosphere's size and shape are key factors in determining its shielding power from 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. Should IBEX detect changes in the shape of the ribbon, that could show how the heliosphere is interacting with the Local Fluff
Local Interstellar Cloud
The Local Interstellar Cloud is the interstellar cloud roughly 30 light years across through which the Earth's solar system is currently moving. The Solar System is thought to have entered the Local Interstellar Cloud at some time between 44,000 and 150,000 years ago and is expected to remain...
.
In October 2010, significant changes were detected in the ribbon after 6 months, based on the second set of IBEX observations.