THE ROLE OF GRAIL ORBIT DETERMINATION IN PREPROCESSING OF GRAVITY SCIENCE MEASUREMENTS

摘要

The Gravity Recovery And Interior Laboratory (GRAIL) mission has constructeda lunar gravity field with unprecedented uniform accuracy on thefarside and nearside of the Moon. GRAIL lunar gravity field determination beginswith preprocessing of the gravity science measurements by applying correctionsfor time tag error, general relativity, measurement noise and biases.Determining these corrections requires the generation of spacecraft ephemeridesof an accuracy not attainable with the pre-GRAIL lunar gravity fields.Therefore, a bootstrapping strategy was developed, iterating between sciencedata preprocessing and lunar gravity field estimation in order to construct sufficientlyaccurate orbit ephemerides. This paper describes the GRAIL measurements,their dependence on the spacecraft ephemerides and the role of orbit determinationin the bootstrapping strategy. Simulation results will be presentedthat validate the bootstrapping strategy followed by bootstrapping results forflight data, which have led to the latest GRAIL lunar gravity fields.