Toward the 1cm Galileo orbits: challenges in modeling of perturbing forces
Abstract
Precise orbit determination demands knowledge of perturbing forces acting on the satellites of the Global Navigation Satellite Systems (GNSS). The metadata published by the European GNSS Agency for the Galileo satellites allow for the composition of the analytical boxwing model dedicated for coping with the direct solar radiation pressure (SRP), albedo, and infrared radiation (IR). Based on the boxwing model, we evaluated both the magnitude and the characteristic periods of accelerations caused by all the aforementioned forces. We assess which perturbations can be absorbed by the extended Empirical CODE Orbit Model (ECOM2) and what are the consequences of neglecting higherorder ECOM2 coefficients. In order to evaluate the impact of SRP, albedo, IR, and the navigation antenna thrust, we perform a series of precise Galileo orbit determination strategies for Galileo InOrbitValidation (IOV), Full Operational Capability (FOC), and two FOC satellites launched into eccentric orbits. The proposed boxwing model is capable of absorbing approximately 97% of the SRP in the Sunsatellite direction, whereas the rest can be mitigated by an additionally estimated small set of empirical parameters. The purely physical boxwing model does not fully handle satellite misorientation and reradiation effects, such as Ybias, solar panel rotation lag, that is the misalignment causing a constant acceleration perpendicular to the solar panel axis and the direction to the Sun. However, the boxwing model is especially crucial in terms of the absorption of the higherorder terms of SRP and stabilizes the orbit solutions during the eclipsing periods. Based on the SLR residual analysis, we found a systematic effect at the level up to 50 mm resulting from the omission of the highorder empirical orbit coefficients. We also found that the impact of the albedo, IR, and transmitter antenna thrust on the Galileo orbits reach the level of 5, 14, and 20 mm, respectively. Eventually, we obtain the overall accuracy of the GalileoFOC orbits at the level of 22.5 mm, even for the eclipsing period for the solution which considers the boxwing model with the estimation of the constant empirical accelerations.
 Publication:

Journal of Geodesy
 Pub Date:
 January 2020
 DOI:
 10.1007/s00190020013422
 Bibcode:
 2020JGeod..94...16B
 Keywords:

 Galileo;
 GNSS;
 Precise orbit determination;
 Solar radiation pressure;
 Albedo;
 MGEX