Trajectory computation during a maneuver: Thrust estimation with the Goddard Trajectory Determination System (GTDS)

Existing thrust modeling capabilities of the Goddard Trajectory Determination System (GTDS) have been enhanced to allow calibration of the onboard propulsion system. These enhancements provide one or more thrust scale factors, based on estimation using the batch least-squares technique, for the case of along-track thrust and the case of attitude-dependent thrust. The enhancements are evaluated using simulated tracking measurements for a test spacecraft and using actual tracking measurements for the Earth Radiation Budget Satellite (ERBS). The effects of tracking measurement noise and distribution on the accuracy of the estimation are investigated and found to be significant. Results and conclusions of the analysis are presented.