Accounting for perturbing forces acting on Galileo using a box-wing model

Abstract

In November 2017, the European Global Navigation Satellite System Agency (GSA) released geometrical and optical information for the Galileo satellites which allowed for the composition of a box-wing model whose main goal is absorption of the direct solar radiation pressure, earth’s albedo, and infrared radiation. In order to evaluate the efficiency of the box-wing model, we test solutions based solely on the empirical models, the pure analytical box-wing model, and a series of hybrid models including the box-wing with different sets of additionally estimated empirical parameters. The hybrid solution, which is based on the box-wing model and on a reduced number of estimated empirical parameters, substantially reduces variabilities of the satellite laser ranging (SLR) residuals, especially for the low elevation angles of the sun above the orbital plane (β), i.e., for eclipsing Galileo satellites. The standard deviation of SLR residuals for |β| < 12.3° decreases from 37 to 25 mm between the solution based on the ECOM2 and the hybrid solution, respectively. We found significant mitigation of the spurious geocenter signal in the Z component and its formal errors, when reducing the number of estimated empirical parameters, and a substantial reduction of the dependency between geocenter coordinates, the geometry of Galileo orbital planes, and the position of the sun. The hybrid box-wing solution with a reduced set of empirical parameters provides thus the best solution for precise orbit determination, orbit predictions, and estimation of geodetic parameters.