New Satellite Orbit Determination Method Enhances Navigation Precision for Mega-Constellations

Precise orbit determination (POD) is crucial for the accuracy of satellite navigation, positioning, and timing services, especially with the expansion of large Low Earth Orbit (LEO) constellations. A groundbreaking method developed by researchers integrates inter-satellite link (ISL) data with onboard BeiDou-3 (BDS-3) observations to simultaneously determine the orbits of both LEO and BDS-3 Medium Earth Orbit (MEO) satellites. This technique addresses the challenge of systematic constellation rotation by referencing the coordinate system implied in BDS-3 broadcast ephemerides and applying a rotation correction. Simulations demonstrate that this approach reduces LEO orbit errors from over 20 cm to about 1 cm, offering a solution that is both high in accuracy and low in latency, without heavy dependence on ground tracking stations.

The significance of this development cannot be overstated, as modern satellite constellations like OneWeb, Starlink, and CENTISPACETM aim to provide global communications and navigation capabilities using LEO constellations. Traditionally, their POD has required dense networks of ground stations, which are not only costly but also limited by geopolitical or geographical constraints. The new method leverages inter-satellite links (ISLs) to reduce ground dependence, overcoming the issue of 'rotational unobservability'—a phenomenon where the entire constellation drifts in orientation due to the lack of an absolute spatial reference. Published in Satellite Navigation, the study showcases how the technique achieves centimeter-level precision, marking a significant leap forward in satellite navigation technology.

Dr. Kecai Jiang, the corresponding author of the study, highlights the method's ability to tackle one of the most persistent issues in autonomous constellation orbit determination. By utilizing readily available BDS-3 broadcast ephemerides and inter-satellite measurements, the technique delivers unprecedented precision without the need for post-processed GNSS products or extensive ground networks. This innovation is not only efficient but also scalable, promising to revolutionize real-time, high-accuracy navigation services for future mega-constellations. The potential applications of this technology are vast, ranging from global navigation augmentation to autonomous LEO-based navigation systems and real-time positioning services, offering a resilient solution for operations in remote or geopolitically constrained regions.