Towards a high-precision analytical radiation force model for the GPS IIF spacecraft

We present the status of our work on producing a new high-precision, physics-based radiation force model for the GPS IIF spacecraft. The details of the spacecraft model, i.e. geometry and surface material properties, are given. The methods used to build the spacecraft model from various information sources are described. Overall, the radiation force model accounts for the direct solar force, the recoil force due to reflected (diffuse and specular) radiation, and also thermal forces (re-radiation and solar panel thermal gradient). The bus component of the radiation force model is computed using ray-tracing techniques. The performance of the new model is compared against one that uses a box-wing spacecraft model. The assumptions and limitations of the modelling are discussed.