Modeling range biases from SLR residuals to GNSS-based orbits of active Low Earth Orbiters – insights from a study based on a dozen of satellites and 21 years of data

Abstract Satellite Laser Ranging (SLR) is a space geodetic technique that substantially contributes to the determination of global geodetic parameters and the realization of terrestrial reference frames. For active Low Earth Orbiters (LEOs), SLR typically serves as an independent validation technique of Precise Orbit Determination (POD) products based on Global Navigation Satellite Systems (GNSS). However, range biases (RBs) significantly limit the current accuracy of SLR observations. We test different modeling of RBs in SLR validation for a dozen of LEOs: GRACE-A/B/C/D, SWARM-A/B/C, Sentinel-3A/B, CHAMP, TerraSAR-X, and TanDEM-X, tracked by International Laser Ranging Service (ILRS) stations over 21 years (2002–2023). We evaluate applying no RB correction, using RBs provided by the ILRS based on LAGEOS-1/2 satellites, and estimating RBs at weekly/monthly/yearly intervals based on GNSS-based orbits. Omitting RB corrections results in increased SLR residuals of LEO orbits, with offsets of 1–6 mm and standard deviations (std) of 16–25 mm. The RB corrections estimated by us generally remain within ± 10 (30) mm for high-performing (other) stations. Applying the ILRS LAGEOS-1/2-based RBs increases residual offsets by ~ 2 mm and std by 3–7 mm. Incorporating our RBs estimated at weekly/monthly resolutions improves SLR validation results, reducing offsets to ~ 0.5 (~ 1) mm and std to 9–22 (12–23) mm of high-performing (all) stations. These reductions correspond to a 60–86% mean offset improvement and a 9–15% std reduction compared to no RB solution. Monthly station-satellite-specific RBs enhance SLR validation of LEOs by balancing temporal stability, parameter estimation efficiency, and consistency with POD products.