Applicability of GPS-based Orbit Determination Systems to a Wide Range of HEO Missions

Alessandro Pasetti, Jorge Potti and Pelayo Bemedo

Abstract:	This paper presents the most significant objectives, results and conclusions of the “Study on Orbit Deter- mination for Satellites at HEO”. This study was pro- moted by the European Space Research and Technol- ogy Centre (ESTEC) and was developed by GMV S.A. One of its major objectives is the investigation of dif- ferent real-time orbit determination techniques for ap- plication on-board satellites operating in highly ellipti- cal orbits (HEO). The study addresses those technical areas of particular concern towards the applicability of GPS to the orbit determination of satellites at HEO. Among others, we must mention techniques for attenuating the disturbing effect of the ionosphere and of selective availability, the problem of the link budget at high altitudes, inves- tigations of GPS antenna(s) configuration optimality, the need for an on-board propagation model, tech- niques for attenuating the disturbing effect of orbit con- trol manoeuvres and the importance of the GPS-re- ceiver clock stability. Four HE0 scenarios were considered during the study (M-HE0(8), Molniya, Tundra and ISO-type orbit). For each scenario, computer simulations were performed to ascertain the achievable orbit determination accuracy. The results show that for typical HE0 telecommunica- tion missions (on M-HE0 or Molniya orbits) a single GPS antenna connected to a low-cost GPS receiver and implementing a relatively simple Kalman filter with a low-cost orbit dynamics model, is able to provide an orbit positioning accuracy in the order of 100 m. Such orbit determination accuracy is sufficient for many HE0 applications. Some HE0 scientific missions in ISO-type of orbit, however, require higher accuracies. Our study demonstrates that for such missions the maximum achievable accuracy implementing state-of- the-art GPS technology lies in the order of 10 m. For HE0 missions in Tundra orbit the achievable orbit de- termination accuracy lies in an approximate rage of 50- 100 m depending on the quality of GPS technology implemented. Extrapolations to GE0 from the Tundra case becomes also possible from the results of the study.
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:	589 - 598
Cite this article:	Pasetti, Alessandro, Potti, Jorge, Bemedo, Pelayo, "Applicability of GPS-based Orbit Determination Systems to a Wide Range of HEO Missions," 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. 589-598.
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