GPS-based Accelerometry Performance for the CHAMP, GRACE and GOCE Satellites
van den IJssel, Jose; Doorbos, Eelco; Visser, Pieter
Faculty of Aerospace Engineering, Delft University of Technology, NETHERLANDS
With the recent advances made in gravity field modeling, it is feasible to determine accurate non-gravitational accelerations indirectly from precise GPS satellite-to-satellite observations. With the growing number of satellites equipped with a high-quality GPS receiver, this so-called GPS-based accelerometry method could be applied to a large range of satellites. Such a data set of recovered non-gravitational accelerations offers great potential for the improvement of atmospheric density models.
An assessment is made of the GPS-based accelerometry performance using GPS data from the CHAMP, GRACE and GOCE satellites. These satellites carry high-quality GPS receivers, which is essential for a good performance of the GPS-based accelerometry approach. Due to their low altitude, ranging from around 250 to 450 km, these satellites experience relatively large non-gravitational accelerations, which makes them very interesting for atmospheric density and wind modeling. Furthermore, these satellites carry electrostatic accelerometer instruments, making it possible to validate the performance of the GPS-based accelerometry experiments.
Using a state-of-the-art gravity field model, two months of CHAMP and GRACE GPS data have been processed. For GOCE, two sets of GPS data are processed, consisting of a 2-month period when the satellite was in nominal Drag Free Control (DFC) flight and a 9-day period when the DFC was switched off. The resulting non-gravitational accelerations have been compared with the onboard observations, as well as with state-of-the-art non-gravitational force models. In flight direction, the GPS-based accelerometry method shows better agreement with the measured accelerations than the modeled accelerations, which indicates that the results can be applied for improvement of these models.