| Operator | NASA |
|---|---|
| Mission type | Orbiter (observatory) |
| Satellite of | Earth |
| Orbital insertion date | 2008-10-19, 18:21:00 UTC |
| Launch date | 2008-10-19, 17:47:23 UTC |
| Carrier rocket | L-1011 Stargazer / Pegasus XL |
| Launch site | Air-launch, near Kwajalein Atoll |
| Mission duration | ~2 years elapsed: 3 years, 4 months and 6 days |
| COSPAR ID | 2008-051A |
| Homepage | http://www.ibex.swri.edu/ |
| Mass | 110 kg (243 lb) |
| Power | 85 watts |
| Orbital elements | |
| Eccentricity | 0.8829530 |
| Inclination | 51.5° |
| Apoapsis | 300,329.7 km |
| Periapsis | 12,693.9 km |
| Orbital period | 7.571989 d ( 10,903.7 min ) |
| Orbits per day | < 1 |
| Instruments | |
| Main instruments | IBEX-hi, IBEX-lo |
| References: [1][2] | |
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.[3] 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.[1]
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The heliospheric boundary of the Solar System 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 8,000 kilometres (5,000 mi) to an apogee of about 300,000 kilometres (190,000 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 (70,000 kilometres / 43,000 miles), 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.[3] By launching from this site close to the Equator, the Pegasus rocket lifted as much as 35 pounds (16 kg) more mass to orbit than it would have with a launch from the Kennedy Space Center in Florida.[4]
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.[5] The L-1011 arrived at Kwajalein Atoll on Sunday, October 12, 2008.[6]
IBEX is collecting Energetic neutral atom (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.[7]
Initial data revealed a previously unpredicted "very narrow ribbon that is two to three times brighter than anything else in the sky".[8] Initial interpretations suggest that "the interstellar environment has far more influence on structuring the heliosphere than anyone previously believed".[7] "No one knows what is creating the ENA (energetic neutral atoms) 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".[9] 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 rays. Should IBEX detect changes in the shape of the ribbon, that could show how the heliosphere is interacting with the Local Fluff.[10]
In October 2010, significant changes were detected in the ribbon after 6 months, based on the second set of IBEX observations.[11]
"Our discovery of changes over six months in the IBEX ribbon and other neutral atoms propagating in from the edge of our solar system show that the interaction of our Sun and the galaxy is amazingly dynamic"—David J. McComas, IBEX principal investigator [11]
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