Preliminary Navigation System Design for the First LCRNS Satellite Providing Lunar PNT Services

Tara Mina, Ava Thrasher, Mark Hartigan, Jason Leonard, Shaun Stewart, Peter Antreasian, Kevin Pipich, Daniel Brack, David Gaylor, Barrett Bedford-Dillow, E. Glenn Lightsey, John Christian

Abstract:	The next decade will see the establishment of a sustainable human and robotic presence on the Moon, with navigation and communication capabilities playing a critical role in supporting Artemis and future lunar missions. To enable reliable Positioning, Navigation, and Timing (PNT) services over the lunar South Pole, Intuitive Machines will deploy a constellation of Lunar Data Network (LDN) navigation satellites compliant with NASA’s Lunar Communication Relay and Navigation System (LCRNS) requirements, beginning with LDN-1 in late 2026. This paper presents the design and preliminary performance analysis of LDN-1’s autonomous onboard navigation system. The architecture leverages weak-GNSS pseudoranges and time-differenced carrier phase (TDCP) as the primary measurement source, with onboard optical navigation (visual odometry and horizon-based) included for supplementary sensing modalities to maintain orbit knowledge during GNSS outages and to provide independent onboard validation. Simulation results over a 14-day period show that, using onboard measurements alone, the weak-GNSS and OpNav configuration maintains peak 3? error contributions of about 8 m to the position SISE and 1?1.3 mm/s to the velocity SISE while LDN-1 remains within the initial operating capability (IOC) service volume. Brief exceedances of the allocated estimation-error contributions occur near perilune, just as LDN-1 is exiting the service volume. These results validate the preliminary onboard navigation design and indicate that LDN-1 can maintain reliable orbit determination and timing, closely approaching the desired system performance even without leveraging terrestrial support.
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:	2909 - 2946
Cite this article:	Mina, Tara, Thrasher, Ava, Hartigan, Mark, Leonard, Jason, Stewart, Shaun, Antreasian, Peter, Pipich, Kevin, Brack, Daniel, Gaylor, David, Bedford-Dillow, Barrett, Lightsey, E. Glenn, Christian, John, "Preliminary Navigation System Design for the First LCRNS Satellite Providing Lunar PNT Services," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 2909-2946. https://doi.org/10.33012/2025.20351
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