93-157
Preliminary Gps Orbit Determination Results For The Extreme Ultraviolent Explorer,
Kenn Gold*, Willy Bertiger**, Sien Wu***, and Tom Yunck****
Abstract
A Single-frequency Motorola GPS reciever was launched with the Extreme Ultraviolent Explorer mission in June 1992. The reciever utilizes dual GPS antennas placed on opposite sides of the satellite to obtain full GPS coverage as it rotates during its first primary scanning mission. A data set from this GPS experiment has been processed at the Jet Propulsion Laboratory with GIPSY-OASIS II software package. The single-frequency, dual antenna approach and the low altitude (~500 km) orbit of the satellite create special problems for the GPS orbit determination analysis. Low orbit implies that the dynamics of the spacecraft will be difficult to model, and that atmospheric drag will be an important error source. A reduced dynamic solution technique was investigated in which ad hoc accelerations were estimated at each time step to absorb dynamic model error. In additon, a single frequency ionospheric correction was investigated, and a cucle-slip detector was written. Orbit accuracy is currently better than 5 m. Further optimization should improve this to about 1 m.
* Research Assistant, Colorado Center for Astrodynamics Research, University of Colorado, Campus Box 431, Boulder, Colorado 80309.
** Member of Technical Staff, Tracking Systems and Applications Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.
*** Technical Group Leader, Tracking Systems and Applications Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.
**** Deputy Section Manager, Tracking Systems and Applications Section, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109.