Comparative Analysis and Design of a Dual-Satellite System for Lunar Rover Localization

The renewed international focus on lunar exploration has highlighted the need for autonomous localization services for lunar surface users. NASA's Endurance rover, tasked with traversing 2 000 km of the Moon's South Pole Aitken basin, is one such surface user that will require precise localization. The Lunar Pathfinder satellite is expected to maintain communication with the Endurance rover throughout its mission, enabling the possibility for satellite-based navigation. However, a key limitation of this approach is the poor observability and the lack of measurement diversity when relying on a single satellite. This paper presents a comparative analysis of the state estimation performance with the integration of a second communication satellite into the current planned configuration. We propose an optimized orbital design for the second satellite that maximizes coverage of the lunar South Pole region based on metrics such as line-of-sight visibility to the rover and position dilution of precision (PDOP). Additionally, we incorporate realistic error modeling that considers the receiver thermal noise, clock stability, and satellite ephemeris errors to best represent the scenario in simulation. The dual-satellite constellation design is able to localize the rover to sub-10-m accuracy in less than 1.11 hours on average, achieving a time reduction of 85.2% To 96.6% compared to the single-satellite scenario, depending on the rover's location. Note that this localization accuracy is achieved without a dedicated navigation payload onboard either satellite. These findings contribute to the development of more robust autonomous localization solutions for future lunar exploration.