A new solar radiation pressure model for GPS

Abstract

The largest error source in GPS orbits is due to the effects of the solar radiation pressure. Over the last few years many improvements were made in modeling the orbits of GPS satellites within the IGS. However, most improvements were achieved by increasing the number of estimated orbit and/or solar radiation pressure parameters. This increased number of estimated satellite parameters weakens the solutions of all estimated parameters. Due to correlations, the additional parameters may cause biases in other estimated quantities like, e.g., the length of day. In this paper we present a recently developed solar radiation pressure model for the GPS satellites. This model is based on experiences and results acquired at the Center of Orbit Determination in Europe (CODE) in the context of its IGS activities since June 1992. The new solar radiation pressure model outperforms the existing ROCK models by almost an order of magnitude. It also allows a reduction of the number of orbit parameters that have to be estimated.