Detecting Orbital Debris in LEO and MEO Using GNSS Signals for Passive Space Surveillance and Collision Risk Assessment

This paper investigates the use of Global Navigation Satellite System (GNSS) signals to detect orbital debris in Low Earth Orbit (LEO) and Medium Earth Orbit (MEO). The motivation stems from the exponential threat of the collision cascade effect, where space debris collisions generate more debris, threatening the sustainability of orbital environments. By leveraging the Doppler effect and the debris motion equation in the Earth-Centered, Earth-Fixed (ECEF) frame, the direct and reflected signals were analyzed using Two-Line Element (TLE) data for four major collisions: Cosmos 2251, Iridium 33, Breeze-M, and Fengyun-1C. The Doppler shift ranged from ~30 kHz in LEO to ~2 kHz in MEO, illustrating the sensitivity variation due to orbital altitude. Phase change rate analysis revealed the disordered motion of debris. Comparative simulations confirmed the improved detection capability at lower altitudes and validated the adopted GNSS-based methodology, which can serve as a low-cost and novel alternative for studying space debris. This method also leverages existing satellite infrastructure.