Session A4: PNT Solutions for Space Applications

High Precision Spacecraft Landing on the Moon Through Lunar Satellite Navigation Systems and Local Ultra-Wideband Positioning Network
Danim Jung and Euiho Kim, Hongik University
Location: Beacon A
Date/Time: Thursday, Jan. 30, 10:40 a.m.

NASA and ESA have recently initiated Lunar Navigation Satellite System (LNSS) development programs to support upcoming lunar exploration missions. Unlike terrestrial Global Navigation Satellite Systems (GNSS), LNSS positioning accuracy is expected to be limited to several tens of meters due to constraints in monitoring and control infrastructure. This study explores a hybrid positioning approach that combines LNSS and an Ultra-Wideband (UWB) network to enhance precision landing for spacecraft on the Moon. We considered recently proposed LNSS constellations and operational concepts, along with a UWB network optimized for lunar surface operations using an in-house genetic algorithm. The UWB network layout was designed based on RF signal propagation characteristics and landing-phase accuracy requirements. To mitigate the positional uncertainty of rover antennas, which can reach several tens of meters with LNSS alone, we implemented a cooperative positioning (CP) technique that integrates LNSS and UWB-based inter-rover ranging, along with a post-process filtering method to further refine the estimated positions. This approach reduced rover antenna positioning errors to 5 meters or less (RMS). Simulation results confirm that the optimized UWB network, when integrated with LNSS and an altimeter, significantly improves spacecraft positioning accuracy, maintaining consistent performance regardless of LNSS constellation geometry and ensuring sufficient horizontal positioning accuracy up to 150 m altitude along the landing trajectory.