Long-term prediction of GPS satellite orbit

The issue of long-term prediction of GPS satellite orbit is addressed in this paper. Instead of the curve-fitting method, Newton's equations of motion for the satellite is integrated to predict the position of the GPS satellites in a few days. Various effects, including that of the non-spherical Earth, the Sun-Earth gravitational force, and Solar radiation pressure, are taken into account. From the numerical result, it is shown that the prediction error can be significantly reduced after those perturbations being included.