GPS Tracking of Space Systems in Transfer Orbit

R. W. Benson, J. L. Yang, P. H. Kim, A. Y. Lee, G. T. Tseng, T. B. Scruggs

Abstract:	Because of the maturity of the GPS technology and its apparent cost and operational benefits over com-peting approaches, DoD mission planners are increas-ingly interested in integrating GPS-based navigation into future satellite systems architectures. Although using GPS for low earth orbit satellite navigation has been successfully demonstrated and well documented, GPS-based high altitude navigation still poses unique technical challenges. Each satellite in the current GPS constellation (II and II A) and its follow-ons (II R and II F) is de-signed to broadcast its navigation messages within an L-Band cone that barely contains the earth. Users on or near the earth surface, such as cars, aircraft, or even low earth satellites, can always see a sufficient num-ber of GPS satellites for a good navigation solution. As a user moves up in altitude and reaches regions not covered by those L-band cones, there may not be enough visible GPS satellites for a good navigation solution. Furthermore, a user vehicle in transfer orbit to geosynchronous orbit (GEO) can experience signif-icant delta-V burns, attitude maneuvers, and thermal rolls. This highly dynamic environment poses addi-tional challenges for an integrated GPS-based naviga-tion approach. Recent research on high altitude GPS applications includes using the L-Band signal aided by an atomic clock for GEO satellites and the L-Band integrated with the GPS cross-link signal for IUS. In this paper, only the L-band signal is used for a unique satellite transfer orbit scenario involving three delta-V burns to place the satellite into its final geosynchronous or-bit. An on-board GPS receiving antenna study was conducted for several different antenna configurations. The results indicate that two quarter-wave patches provide a good compromise between GPS visibility and implementation cost. One patch is placed so that its line of sight is parallel to the satellite spin axis, while the other patch is placed with its line of sight per-pendicular to the spin axis. With this configuration, roughly 2500 meter (1 u) accuracy is obtainable af-ter a delta-V burn and that the accuracy quickly con-verges to better than 100 meters. By changing the launch time, the resulting change in visibility can im-prove the accuracy by more than 1500 meters during delta-V burns.
Published in:	Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997) September 16 - 19, 1997 Kansas City, MO
Pages:	763 - 768
Cite this article:	Benson, R. W., Yang, J. L., Kim, P. H., Lee, A. Y., Tseng, G. T., Scruggs, T. B., "GPS Tracking of Space Systems in Transfer Orbit," Proceedings of the 10th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1997), Kansas City, MO, September 1997, pp. 763-768.
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