GNSS Orbit Prediction with Enhanced Solar Radiation Pressure Model

Abstract

To serve real-time users, orbit prediction is in most cases used to provide real-time GNSS (Global Navigation Satellite System) orbit products. With precise Solar Radiation Pressure (SRP) model and sufficient ground tracking stations in orbit determination, the IGS (International GNSS Service) states that the officially published GPS Ultra-rapid (IGU) orbit products are prepared with 1D mean RMS of 5 cm. However, for the new emerging satellites the prevailing Empirical CODE Orbit Models (ECOM, ECOM2) are not always good enough, especially if the spacecraft is a stretched body satellite. In our former study, we showed that the use of an a priori box-wing (BW) model by taking our adjusted optical parameters enhanced the ECOM model and resulted in the best results for Galileo, BeiDou-2 GEO, BeiDou-3e and QZS-1 satellite orbits. In this contribution, we test the performances of ECOM, ECOM+BW, ECOM2 and ECOM2+BW models in orbit prediction. Daily precise orbits by using individual SRP models are taken as observed orbits. Consistencies between 3-h predicted orbits and precise orbits for individual SRP models are evaluated. Results show that the pure ECOM2 model performs in general better than the pure ECOM model for the stretch body satellites. The ECOM+BW model results in the best predictions for Galileo, BeiDou-2 GEO and QZS-1 satellites, for which the improvement of 3D RMS is about 10%, 50% and 60% respectively over the pure ECOM model. BeiDou-2 IGSO, MEO and BeiDou-3e predictions do not benefit much from the a priori box-wing model.