Navigation Filter Design for an LCRNS Receiver during Lunar Powered Descent and Landing

Mark Hartigan, Frank Garcia, E. Glenn Lightsey, Shaun Stewart

Abstract:	Several international organizations, in collaboration with private partners, are actively mobilizing towards a sustainable presence on the Moon. Key among them is NASA, along with their LunaNet partners ESA and JAXA. Under a NASA Near Space Network Subcategory 2.2 contract, Intuitive Machines (IM) will be deploy and operate five communications and navigation satellites in lunar orbit; these satellites will provide position, navigation, and timing to lunar users equipped with an S-band receiver in a manner similar to terrestrial global navigation satellite systems (GNSSs). In this work, we examine the signal-in-space errors generated by IM’s satellite constellation. Then, the performance of a notional S-band receiver is derived and analyzed for a hypothetical lunar landing during powered descent near the lunar South Pole. Pseudorange, time-differenced carrier phase, and Doppler shift measurements are synthesized in a delayed-state extended Kalman filter – aided by an inertial measurement unit – to determine achievable performance for a lunar lander during periods of coverage by IM’s five-satellite constellation. Our preliminary results show position and velocity navigation errors during landing < 30 m 3? and < 3 cm/s 3?, indicating compliance with NASA-levied requirements. However, measurement biases due to more advanced modeling of errors sources cause inconsistencies between the estimate covariance and true error, prompting further work.
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:	2947 - 2962
Cite this article:	Hartigan, Mark, Garcia, Frank, Lightsey, E. Glenn, Stewart, Shaun, "Navigation Filter Design for an LCRNS Receiver during Lunar Powered Descent and Landing," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 2947-2962. https://doi.org/10.33012/2025.20260
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