Precise orbit determination and accelerometer data modelling of the GRACE Follow-On mission

Precise orbit determination is a major objective in satellite geodesy and data analysis of several satellite missions observing Earth or another planet. Satellite gravity missions such as the Gravity Recovery And Climate Experiment (GRACE) Follow-On mission, require high level of orbit precision (cm level) in order to capture the gravity field modelling of static and time-variable components. The mission’s on-board accelerometers form a key instrument for the direct measurement of non-gravitational perturbations. The accelerometry data processing is crucial for accelerometers with reduced performance following the launch into space such as the case of one of the GRACE-FO satellites. The current study focuses on the GRACE-FO accelerometer calibration modelling within a scheme of precise orbit determination. In particular, the estimation of accelerometer calibration parameters includes bias, drift and scale factors in combination with a minimum number of empirical forces of cycle-per-revolution terms and bias accelerations. The consideration of such empirical perturbations aims at capturing periodic mismodelling effects and accelerometer data errors. The applied approach leads to orbital residuals varying within a few mm to cm while the inter-satellite LRI and KBR range-rate data residuals vary within a few μm/sec.