Global Positioning System (GPS) Enhanced Orbit Determination Experiment (GEODE) on the Small Satellite Technology Initiative (SSTI) Lewis Spacecraft

Roger C. Hart, Kathy R. Hartman, Anne C. Long, Taesul Lee and Dipak H. Oza

Abstract:	The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center is currently developing the capability to use the Global Positioning System (GPS) to provide high-accuracy attitude, orbit, and time autonomously onboard NASA spacecraft. NASA’s Small Satellite Technology Initiative Lewis spacecraft will host the GPS Attitude Determination Flyer (GADFLY) experiment. The primary objective of GADFLY is to demonstrate the use of GPS onboard for autonomous attitude and orbit determination and precise time distribution. GADFLY includes the GPS Enhanced Orbit Determination Experiment (GEODE) to flight qualify NASA-developed navigation algorithms for high- accuracy real-time onboard orbit determination. The GEODE flight software is designed to be hosted either on the GPS receiver’s digital receiver/processor unit or the primary spacecraft computer. GEODE executes a background Kalman filter and a foreground real-time state propagator, outputting position and velocity data every 1.0 second. Preflight processing of raw pseudorange measurements from existing spaceborne GPS ‘receivers indicates that the GEODE navigation algorithms should provide a real-time total position accuracy of better than 10 meters (lo) and velocity accuracy of better than 0.01 meter per second (la), with Selective Availability at typical levels. On-orbit performance will be assessed by comparing GEODE autonomous solutions with solutions obtained by differential postprocessing of GPS measurements.
Published in:	Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996) September 17 - 20, 1996 Kansas City, MO
Pages:	1303 - 1312
Cite this article:	Hart, Roger C., Hartman, Kathy R., Long, Anne C., Lee, Taesul, Oza, Dipak H., "Global Positioning System (GPS) Enhanced Orbit Determination Experiment (GEODE) on the Small Satellite Technology Initiative (SSTI) Lewis Spacecraft," Proceedings of the 9th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1996), Kansas City, MO, September 1996, pp. 1303-1312.
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