GPS-based dynamic orbit determination for low Earth orbit satellites

A classical reduced-dynamic GPS-based Precise Orbit Determination (POD) strategy for Low Earth Orbit (LEO) satellites is often based on a limited explicit modelling of satellite dynamics and modelling deficiencies are compensated by numerous empirical parameters. With better gravitational models and the advances in satellite surface force modeling, uncertainties in the satellite dynamics are significantly reduced. Furthermore, single-receiver ambiguity resolution allows for more robust POD as well. Therefore, a dynamic POD strategy using significantly fewer estimated empirical parameters can be implemented to generate dynamic orbits, which allow for force modeling sensitivity analyses and evaluating potential errors in the adopted GPS antenna reference points or phase center offsets, etc. This presentation outlines the recent dynamic POD methodology developments at the Astronomical Institute of the University of Bern (AIUB) and investigates the POD performances for a few dedicated space geodesy satellite missions (Swarm, GRACE-FO, Sentinel-1, Sentinel-2, Sentinel-3 and Jason-3) that are operated at altitudes ranging from 430 to 1350 km. The focuses will be on satellite gravitational and non-gravitational force modeling, satellite dynamics parametrization, and orbit validations for different types of satellites. Results reveal that the dynamic POD strategy is flexible and robust to generate high-quality orbits for those satellites, showing reliable agreements with the independent ambiguity-fixed kinematic orbits and the external Satellite Laser Ranging (SLR) measurements.