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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 was two years to observe the entire solar system boundary. This prime mission was achieved by 2011, and because it was so successful the mission was extended to 2013. In June 2011, IBEX was shifted to a new more efficient orbit. Results from IBEX shocked the scientific community and overturned old theories when it showed a narrow ribbon of energetic neutral atom (ENA) emission.  Another shock came when it showed shifts over time in this band. It has also observed the Earth's magnetosphere and neutral atoms from outside the solar system. 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. 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 (16 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.

Fig 1: Interstellar Boundary Explorer (IBEX)
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. 1.2 Mission parameters

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. IBEX is in a highly-eccentric elliptical terrestrial orbit, which ranges from a perigee of about 43,000 kilometres (27,000 mi) to an apogee of about 310,000 kilometres (190,000 mi), that is, about 80% of the distance to the Moon. Its original orbit was about 7,000 by 320,000 kilometres (4,300 by 200,000 mi), which has changed primarily due to an intentional adjustment to prolong the spacecraft's useful life (see Orbit adjusted below). This very high orbit allows the IBEX satellite to move out of the Earth's magnetosphere when making...
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