Abstract:

The GRACE (Gravity Recovery and Climate Experiment) satellites launched in March 2002 with a Black-Jack GPS onboard receiver on each satellite. Since then, data quality and gravity model as well as background models have been improved significantly. The main purpose of this paper is to investigate how well the GRACE satellite orbits can be determined currently using GPS data. The orbit accuracy is assessed using a number of tests, which include analysis of orbit fits, Satellite Laser Ranging (SLR) residuals, K-Band Ranging (KBR) residuals and external orbit comparison.