Optimal autonomous station keeping of geostationary satellites

The orbit of a geostationary satellite has to be periodically corrected. In existing geostationary satellites the required maneuver is controlled from the ground. The increase of ground operational workload associated with more stringent accuracy requirements and long durations of future geostationary missions has initiated investigations of autonomous station keeping systems as an alternative to ground based orbit control. The subject of autonomous station keeping and related topics have been studied already 20 years ago. The current investigation uses an attitude-independent orbit determination concept and an optimal orbit correction strategy especially designed for low thrust propulsion. The fully autonomous system is based on present or near future technology hardware. Assuming a three-axis stabilized satellite, the measurements of an earth sensor, several sun sensors, and a Polaris sensor are taken in regular time intervals to compute the navigation angles subtended by the earth-sun and the earth-Polaris directions.