Autonomous stationkeeping system for the Lincoln Experimental Satellites (LES) 8 and 9

Stationkeeping of communication satellites by ground control is a major task of the satellite control earth stations. The autonomous east-west stationkeeping systems onboard the Lincoln Experimental Satellites 8 and 9 (LES 8 and 9) were designed to eliminate this ground-control stationkeeping task. This report describes: orbital models, navigation schemes, filtering techniques, control concepts and flight results for the LES 8 and 9 stationkeeping systems. During flight experiments with LES 8, the spacecraft autonomously acquired and maintained the station within + or - 0.06 deg (0.04 deg rms). This represents a major advance in the performance and implementation of autonomous stationkeeping systems. Similar stationkeeping systems for future satellites should reduce ground operations, and contribute to a reliable, maintenance-free satellite system.