CASSINI ORBIT DETERMINATION PERFORMANCE DURING THE FIRST EIGHT ORBITS OF THE SATURN SATELLITE TOUR

摘要

From June 2004 through July 2005, the Cassini/Huygens spacecraft has executed nine successful close-targeted encounters by three of the major satellites (Phoebe, Titan, and Enceladus) of the Saturnian system. During the third orbit the Huy-gens probe was precisely targeted for a successful descent to Titan's surface. Current results show that orbit determination has met design requirements for targeting encounters, Huygens descent, and predicting science instrument pointing for targeted satellite encounters. This paper compares actual target dispersions against the predicted tour covariance analyses. To assess orbit determination performance, post-flyby results are compared to OD predictions. Prediction accuracy of the satellite ephemeris is a key challenge for successful navigation. The improvement of this ephemeris through the orbit determination process is discussed.