Single-Satellite Doppler-Based Localization for Lunar Rovers in Motion

Kaila M. Y. Coimbra and Grace Gao

Abstract:	Early lunar rovers will likely operate before a dedicated lunar navigation constellation is in place, making single-satellite relay links the most practical source of navigation signals for these early-stage rovers. In this work, we study the absolute localization performance using Doppler measurements from a single relay satellite while the rover is moving–a setting that challenges traditional navigation methods due to its intrinsically low observability. Our approach uses the rover’s own motion knowledge (dead reckoning with uncertainty) to relate measurements taken at different times, thereby aggregating multiple geometric viewpoints of the rover’s position through successive satellite passes. We formulate a weighted batch estimator that retains the full measurement history and models conservative uncertainties while treating rover motion as a standard Dubins car kinematic model. Validation is performed in a mission-realistic scenario patterned after NASA’s Endurance rover mission concept and ESA’s Lunar Pathfinder relay satellite in an elliptical lunar frozen orbit. We find that the stop–go mission cadence, which is already required for science imaging and sampling, shortens the time to achieve the desired accuracy by nearly an hour in our study. A sensitivity analysis shows that the system maintains sub-10-m accuracy within two relay orbits (21.68 hours). These results indicate that planned operational dynamics can be leveraged, not merely tolerated, to enable absolute localization for early lunar rovers using a single relay satellite.
Published in:	Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025) September 8 - 12, 2025 Hilton Baltimore Inner Harbor Baltimore, Maryland
Pages:	677 - 688
Cite this article:	Coimbra, Kaila M. Y., Gao, Grace, "Single-Satellite Doppler-Based Localization for Lunar Rovers in Motion," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 677-688. https://doi.org/10.33012/2025.20313
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