Simulation studies on VLBI tracking satellites and the potential to enhance TRF

The accuracy of the Terrestrial Reference Frame (TRF) realization is currently constrained by systematic errors among the four main space-geodetic techniques: GNSS, VLBI, SLR, and DORIS. Terrestrial local ties connect physical survey points from local surveys, which will introduce errors in the TRF and transform uncertainties across all geodetic observations. To achieve the GGOS goals of 1 mm accuracy and 0.1 mm/yr stability for TRF realization, space missions equipped with multiple space-geodetic techniques are proposed, such as GRASP (Geodetic Reference Antenna in Space), E-GRASP, and GENESIS. Space co-location will complement ground-based co-location and enhance the TRF.

We are currently developing the simulated space-geodetic observations of various missions and assessing their potential impact on the TRF including station coordinates, Earth Orientation Parameters, and geocenter. The simulations will take into account VLBI tracking GNSS satellites and geodetic satellites, considering three major error sources: measurement noise, clock error, and zenith wet delay. Through these thorough analyses, we will explore the requirements of this new type of observable. The novel measurement concept has the potential for not only solving the inconsistencies and biases between the different geodetic techniques, but also establishing frame ties between the kinematic and dynamic reference frames.