Precise orbit determination technique to refine spacecraft mechanical modeling

The precise orbit determination of interplanetary spacecraft requires an accurate modeling of the center of mass position with respect to the antenna phase center. Unpredicted variations of this relative position due to events that redistribute the spacecraft mass affect significantly the precision of the radio tracking measurements by inducing spurious Doppler signals. We present a technique to calibrate uncompensated Doppler signals caused by time-varying offsets between the spacecraft center of mass and antenna phase center. This method is applied to the precise orbit determination of the Mars Reconnaissance Orbiter to correct Doppler signatures induced by high-frequency movements of the center of mass due to the re-orientation of the gimbaled appendages (i.e., solar arrays and high gain antenna).