ENHANCED RADIATIVE FORCE MODELING OF THE TRACKING AND DATA RELAY SATELLITES

Orbit determination (OD) approaches operationally model the Tracking a nd Data Relay Satellites (TDRS) as homogenous spheres for nonconservat ive force modeling. To improve definitive orbit determination and pred iction accuracies, and to employ TDRSS tracking of user satellites wit hin various geophysical investigations, a detailed TDRS spacecraft mod el has been developed. The enhanced TDRS model represents the spacecra ft as a combination of twenty-four flat plates. The radiative forces a cting on each plate are computed and vector summed to produce the over all acceleration oil the spacecraft center of mass. An initial model, based on pre-launch engineering information, has been refined to bette r fit observed spacecraft accelerations. The Goddard TDRS-5 Model 3 (G T5M3) improves orbit accuracy, yields better fits to the tracking data , significantly reduces residual accelerations, and improves orbit pre diction capability.