Precise orbit determination and prediction of the ISS in the frame of the ACES mission

The ESA (European Space Agency) fundamental physics mission ACES (atomic clock ensemble in space) on the ISS (International Space Station) has a high demand on orbit determination and orbit prediction accuracy to fulfill its scientific goals. Therefore the experiment will be equipped with a multi-frequency JAVAD GNSS receiver. Due to constructional reasons, the GNSS antenna will be tilted from the zenith by 60° at an azimuth of 50°. In addition the field of view of the antenna will be severely obstructed by the solar panels of the ISS. A simulation study using a GPS signal simulator and a JAVAD GNSS receiver demonstrates the impact of these limitations on a GPS orbit solution of the ISS. The observations recorded by the GPS receiver show small data gaps, but in general the data quality is good enough to generate a continuous orbit and reach the required accuracy.