Simulation of GNSS observations for Genesis-1

A global Terrestrial Reference Frame (TRF) is realized today by four space geodetic techniques, i.e., Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR), Very Long Baseline Interferometry (VLBI), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS). The current goals for the TRF realization are specified with an accuracy of 1 mm and long-term stability of 0.1 mm/year according to the Global Geodetic Observing System requirements.

Differences in the characteristics of each space geodetic technique might introduce systematic effects into TRF realization. Among the crucial systematics, we can distinguish modeling and calibration deficiencies, i.e., direct solar radiation pressure (SRP) modeling for GNSS and DORIS, GNSS antenna calibration uncertainties, South Atlantic Anomaly handling for DORIS, and time and range bias handling for SLR. The current realization of the TRF is based on independent solutions for each of the four contributing space geodetic techniques that are just connected on the ground via local ties and the Earth Rotation Parameters. A new opportunity to challenge the systematic errors is to co-locate space techniques onboard one satellite, as it is planned for the Genesis-1 mission. The Genesis-1 satellite is the first ever satellite co-locating sensors related to GNSS, SLR, DORIS, and VLBI.

In this study, we present preliminary results for orbit reconstruction using simulated GNSS observations for the Genesis-1 satellite. We use the Bernese GNSS Software for different orbital altitudes, including the currently planned altitude of 6000 km. We assess the quality of the orbit reconstruction using simulated GNSS data from observations of the zenith-, nadir-, and both zenith and nadir-looking antennas. Additionally, we assess the visibility from the ground tracking network of VLBI, SLR, and DORIS, for the different satellite altitudes.