Realization of Reference Frames based on Integrated SLR Measurements to LEO and LAGEOS Satellites

Abstract

Numerous active Low Earth Orbiters (LEOs) are equipped with laser retroreflectors used for the Satellite Laser Ranging (SLR) and Global Navigation Satellite System (GNSS) receivers used for positioning. SLR-GNSS co-location onboard LEOs provides a space-based connection of two independent techniques to determine and validate precise LEO orbits. The increasing set of high-quality laser ranges to LEOs with high-quality microwave-based orbits generate the ability to use these observations for various purposes, such as determination of SLR station coordinates or global geodetic parameters. Station coordinates as well as the realization of the International Terrestrial Reference Frame are typically determined using SLR observations to passive geodetic satellites, such as LAGEOS-1/2. In the case of LEOs, such as Sentinel-3A/3B, TerraSAR-X, Jason-2, GRACE-A/B, Swarm-A/B/C, the SLR technique is commonly used for the validation of GNSS-based orbits. Here, we used SLR observations and precise GNSS-derived orbits of these satellites to investigate whether they can be used for the reference frame realization and deriving high-quality station and geocenter coordinates. We present various types of solutions used for the parameter determination, including different solution lengths, SLR ground network constraining, combination of satellites, including LAGEOS data and weighting of observations to investigate the best solution pattern. We compared our results with standard LAGEOS-based solution and show a high consistency of results. SLR observations to active satellites can be used separately and with the combination with geodetic satellites. Combination of observations improves the station coordinates especially for those stations which provide more SLR observations to LEO satellites than to LAGEOS.