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Abstract

In January 2023, International Laser Ranging Service (ILRS) approved the tracking of an additional 20 Beidou-3 Medium Earth Orbit (MEO) satellites as part of the general pool. So far, only 4 BeiDou-3 MEO were tracked. The Beidou satellites employ very advanced GNSS components & technological solutions, but to better identify and understand orbit modeling issues, SLR tracking data is needed. Orbit improvements are needed to consider Beidou in future realizations of terrestrial reference frames and to use them for the co-location of GNSS and SLR in space. In this study, we will summarize the first four months of tracking 24 BeiDou-3 MEO satellites. Moreover, we assessed the quality and availability of the orbit predictions, which allows the ILRS network for tracking and delivering laser observations. IGG UPWR ILRS Associated Analysis Center is heading towards providing independent orbit predictions for GNSS. When using the best-developed processing strategy, we reached the 95th percentile of position errors after the 4th day of prediction equal to 1.7, 2.2, 1.8, 2.2 m for Galileo FOC, GLONASS M, BDS-3 CAST, and QZSS, respectively. Based on the available SLR observations, we validated the BeiDou-3 orbit products delivered by European Space Agency and the Center for Orbit Determination in Europe. The preliminary study proves a decent quality of Beidou-3 orbits, with the standard deviation of SLR residuals reaching 25 mm.