Attitude Determination of the Extreme Ultra-Violet Explorer (EUVE) Using GPS

Eleanor Ketchum and Roger Hart

Abstract:	The EWE spacecrafl, launched in 1992, is equipped with 2 Fixed Head Star Trackers (FHSTs) that provide a “true“ spacecraft attitude to better than 10 arcsecs. EUVE also has a single-frequency Motorola GPS Demonstration Receiver (GPSDR) with dual antennas separated by approximately 1.8 meters. The Flight Dynamics Facility at Goddard Space Flight Center has access to all the above data since launch, providing a unique opportunity to examine the attitude determination capability of GPS with real space flight data. Unfortunately, due to a constraint in the onboard software as well as physical viewing restrictions, the GPS antennas do not stay locked on the same GPS Satellite for more than a few minutes at a time. However, even these relatively small data spans prove fruitful in the quest to properly characterize GPS data for space flight attitude determination. The GPS and truth data used to compute attitudes are presented. Data behavior as well as errors in the comparison between the GPS computed and truth attitudes are e xarnined for several spans of data. Possible error sources are discussed. This work is the beginning of an effort to better understand and characterize the boundaries of GPS attitude determination capabilities using actual space flight data.
Published in:	Proceedings of the 1995 National Technical Meeting of The Institute of Navigation January 18 - 20, 1995 Disneyland Hotel Anaheim, CA
Pages:	775 - 782
Cite this article:	Ketchum, Eleanor, Hart, Roger, "Attitude Determination of the Extreme Ultra-Violet Explorer (EUVE) Using GPS," Proceedings of the 1995 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 1995, pp. 775-782.
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