Earth radiation pressure effects on GPS orbit determination

The radiation pressure efftects on the GPS orbit determination due to solar flux reflected and re-emitted from the earth were investigated. Since the effect of the direct solar radiation pressure dominates on the GPS orbit at its 20,000 km altitude, the earth radiation pressure effects were ignored for most GPS orbit determinations. As the accuracy of GPS orbit determination improves, however, it becomes necessary to include smaller perturbations, such as earth radiation pressure, to improve the orbit determination accuracy further. This paper examines the earth radiation pressure effects on GPS orbit determination using a diffuse earth radiation pressure model implemented in UTOPIA/MSODP1. There were about cm effects on the GPS orbit, especially in the radial component. To access the resulting GPS orbit accuracy, the quality of the estimated geodetic parameters, such as the earth orientation parameters, were evaluated. Also, the Satellite Laser Ranging (SLR) data fit was used as an independent check for the GPS orbit accuracy.