Reduced-Dynamic Orbit Determination of Low-Orbit Satellites Taking into Account GNSS Attitude Errors

Satellite attitude is critical for both satellite antenna phase center offset and phase wind-up correction. However, during the eclipse season, the nominal satellite attitude is almost impossible to maintain, and the satellite attitude variability affects the geometric distance correction of GNSS-LEO satellites, which ultimately affects the orbital accuracy of LEO satellites. To explore the impact of neglecting eclipsing attitude models on LEO satellite orbit determination, this study utilizes the attitude quaternion products provided by CNES to analyze the discrepancies between nominal attitude yaw angles and attitude quaternion-derived yaw angles. It also examines the variations in phase center offset and phase wind-up corrections, caused by neglecting eclipsing attitude models. The model is validated through orbit determination tests using onboard GRACE-FO data from days 90 to 109 of 2023. Based on these analyses, a simplified reduced-dynamic orbit determination model for LEO satellites using attitude quaternion is proposed. It is found that the phase residuals of GRACE-C and GRACE-D under the attitude quaternion strategy are reduced by 3.6% and 3.9%, respectively, and the orbital accuracies of GRACE-C and GRACE-D are improved by 7.3% and 4.5%, respectively, compared with the nominal attitude.