6PS Tracking Experiment of a Free-Flyer Deployed from Space Shuttle

Bob Schutz, P.A.M. Abusali, Christine Schroeder, Byron Tapley, Michael Exner, Rick McCloskey, Russell Carpenter, Michael Cooke, Samantha McDonald, Nick Combs, Courtney Duncan, Charles Dunn, and Tom Meehan

Abstract:	Shuttle mission STS-69 was launched on September 7, 1995, 1099 CDT, carrying the Wake Shield Facility (WSF-02). The WSF-02 spacecraft included a set of pay- loads provided by the Texas Space Grant Consortium, known as TexasSat. One of the TexasSat payloads was a GPS TurboRogue receiver loaned by the University Cor- poration for Atmospheric Research. On September 11, the WSF-02 was unberthed from the Endeavour payload bay using the remote manipulator system The GPS receiver was powered on prior to release and the WSF-02 remained in free-flight for three days before being retrieved on Sep tember 14. All WSF-02 GPS data, which includes dual fiecluency pseudorange and carrier phase, were stored in an on-board recorder for post-flight analysis, but “snap- shots” of data were transmitted for 2-3 minutes at intervals of several hours, when permitted by the telemetry band- width. The GPS experiment goals were 1) an evaluation of precision orbit determination in a low altitude environment (400 km) where perturbations due to atmospheric drag and the Earth’s gravity field are more pronounced than for higher altitude satellites with high precision orbit require- ments, such as TGPEX/PCSEIDGN; 2) an assessment of relative positioning using the WSF GPS receiver and the Endeavour Collins receiver; and 3) determination of atmo- spheric temperature profiles using GPS signals passing through the atmosphere. Analysis of snap-shot telemetry data indicate that 24 hours of continuous data were stored on board, which includes high rate (50 Hz) data for atmo- sphere temperature protiles. Examination of the limited number of real-time navigation solutions show that at least 7 GPS satellites were tracked simultaneously and the on- board clock corrections were at the microsec level, as expected. Furthermore, a dynamical consistency test pro vided a further validation of the on-board navigation solu- tions. Complete analysis will be conducted in post-flight using the data recorded on-board.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	229 - 235
Cite this article:	Schutz, Bob, Abusali, P.A.M., Schroeder, Christine, Tapley, Byron, Exner, Michael, McCloskey, Rick, Carpenter, Russell, Cooke, Michael, McDonald, Samantha, Combs, Nick, Duncan, Courtney, Dunn, Charles, Meehan, Tom, "6PS Tracking Experiment of a Free-Flyer Deployed from Space Shuttle," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 229-235.
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