Optimal geometry for reference frame rotation transformation using VLBI-GNSS space-tie onboard Galileo satellites

Each space geodetic technique realizes its own technique-specific terrestrial frame. Combining the individual techniques requires the links between those frames such as the local tie vectors. Co-location of different geodetic techniques on Earth orbiting satellites offers the unique opportunity of continuously measure ‘space-ties’ which can have a critical role for achieving the Global Geodetic Observing System (GGOS) goal of 1mm accuracy and 0.1mm/year stability of the Terrestrial Reference Frame (ITRF).

We simulate Very Long Baseline Interferometry (VLBI) observations of a broadband VLBI transmitter (VT) onboard Galileo satellites to evaluate the contribution of such a VT space-tie on the rotation transformation between the VLBI and GNSS frames. We investigate the contribution of a VT as space tie by evaluating the formal precision of orientation parameters between the VLBI and GNSS frames using different ground stations/baselines to find the observation geometry for the rotation transformation.