Autonomous Orbit Control of Remote Sensing Spacecraft using Spaceborne GPS Receivers

A study of autonomous orbit control of remote sensing spacecraft using a spaceborne GPS receiver has been performed. To that end, the TerraSAR satellite mission has been chosen as a reference. A new analytical method for the onboard calculation of the satellite`s mean orbital elements and of the deviation of the equator crossing longitude from its nominal values has been developed. Applying the position fixes of a spaceborne GPS receiver as measurements and estimating the satellite mean orbit elements, the deviation of the equator crossing longitude my be derived and be applied to decide on the execution of orbit correction maneuvers. Simulated GPS-measurements have been used for testing the analytical method, and the obtained results are compared with that determined by numerical propagation of the satellite motion. Over the phasing period of TerraSAR orbit, the maximal error of the onboard determination of the equator crossing longitude - the primary parameter in the mission control - does not exceed 230 m in the tests conducted. This achievement provides an important prerequisite for autonomous orbit control, that requires the maintenance of this parameter to 1 km.