Spacecraft Rendezvous by GPS-derived Range and Attitude

Haywood Satz

Abstract:	An algorithm was developed to process GPS measurements and to provide centimeter range, millimeter/second velocity, and milliradian attitude accuracy for a spacecraft in Barth orbiting rendezvous. A Covariance/Monte-Carlo simulator was used to demonstrate effectiveness of the range and attitude- determination algorithm. Models of GPS measurement errors, spacecraft orbital and rotational motions, Inertial Measurement Unit (IMU) errors, and Inertial Navigation System (INS) errors, were developed for that simulator. Covariance time histories were generated to serve as statisticaI predictions of Monte-Carlo-simulated sample- path errors. The system concept, for a NASA mission of spacecraft rendezvous in low Earth orbit, was verified with simulation trials of algorithm operation in the environment of system error sources. Results have shown that a Rendezvous spatxxxaft in 400 km altitude Earth orbit, at 1 km range from a Target vehicle has achieved 40 cm range, 10 mmhec velocity, and 4 mrad of attitude accuracy within a 60 second observation interval. Those results confirmed the analytic predictions of accuracy based on the characteristics of GPS Space, Propagation, and User errors. The close agreement of simulations with analytic predictions has indicated the correctness of developed models, and has demonstrated feasibility of the GPS Rendezvous concept.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	501 - 508
Cite this article:	Satz, Haywood, "Spacecraft Rendezvous by GPS-derived Range and Attitude," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 501-508.
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