This breakthrough mission is achieved with a small, lightweight spacecraft, launched on a Pegasus rocket that is dropped from an airplane. IBEX then uses an additional solid rocket motor and its own onboard propulsion system to boost iteself into a high altitude orbit that reaches 200 thousand miles above the Earth. The IBEX spacecraft is a sun-pointed spinner with 2 narrow angle FOV sensors (IBEX-Hi and IBEX-Lo) that view perpendicular to the spin axis. The payload consists of two imagers specialized to detect neutral atoms from the solar system's outer boundaries and galactic medium.
The IBEX mission design maximizes science viewing time outside of the comparatively bright magnetospheric ENA emissions while maintaining ample performance margins. This is achieved by placing IBEX into a high altitude (37 RE apogee by 7000 km perigee) orbit. During the Phase A study we carried out a comprehensive set of systems engineering trade studies to optimize the approach to achieving this orbit with minimal risk.
Our solution uses a standard Pegasus launch vehicle with IBEX providing an adapter and a STAR 27 Solid Rocket Motor (SRM), which has had 100% success on its 31 flights, as a part of the spacecraft flight system. Just a little over 11 minutes after Pegasus ignition, IBEX is on orbit, traveling toward its high altitude apogee. Our approach to spinning dynamics of the SRM/spacecraft combination is based on expert analysis using proven methods with actual flight data assembled through an exhaustive study and is validated early in the project (Phase B) through scaled testing. Finally, a few days later in commissioning, near the first apogee, we use the spacecraft's hydrazine propulsion system to raise perigee into a low radiation dose orbit.