New Satellite Orbit Determination Method Enhances Precision for Mega-Constellations

The advent of large Low Earth Orbit (LEO) constellations has brought about a need for more precise orbit determination (POD) methods to ensure accurate satellite navigation, positioning, and timing services. A novel approach developed by researchers at Wuhan University 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 method addresses the challenge of systematic constellation rotation by referencing the coordinate system implied in BDS-3 broadcast ephemerides and applying a rotation correction, achieving centimeter-level precision.

Modern satellite constellations like OneWeb, Starlink, and CENTISPACETM aim to provide global communications and navigation capabilities. However, their POD traditionally relies on dense ground station networks, which are costly and limited by geopolitical or geographical constraints. The new rotation-corrected integrated POD method reduces this reliance by leveraging ISL measurements and onboard GNSS observations, offering a more autonomous and low-latency solution. Published in Satellite Navigation, the study demonstrates the method's effectiveness in reducing LEO orbit errors significantly, from over 20 cm to about 1 cm.

The research team simulated a 66-satellite LEO constellation equipped with ISLs and onboard BDS-3 receivers, alongside 24 real BDS-3 MEO satellites. By applying a Helmert transformation to correct the orbits based on rotation angles derived from the integrated POD coordinate frame and the BeiDou Coordinate System, the method achieved remarkable accuracy improvements. This innovation not only enhances the precision of satellite navigation but also lowers hardware requirements and operational costs, making it a scalable solution for future mega-constellations.

Dr. Kecai Jiang, the study's corresponding author, highlighted the method's ability to tackle the persistent issue of systematic rotation in autonomous constellation orbit determination. By utilizing readily available BDS-3 broadcast ephemerides and inter-satellite measurements, the approach delivers centimeter-level precision without the need for post-processed GNSS products or extensive ground networks. This advancement holds significant promise for global navigation augmentation, autonomous LEO-based navigation systems, and real-time positioning services, paving the way for enhanced global navigation and timing performance.