Constellation Design and Staged Deployment for the Lunar Navigation Satellite System

Keidai Iiyama and Grace Gao

Abstract:	The establishment of a sustainable human presence on the Moon demands robust positioning, navigation, and timing (PNT) services that can support both surface and orbital operations. Current lunar navigation system proposals focus on early deployment of elliptical lunar frozen orbits (ELFO) for South Pole coverage, but there remains no unified framework for designing constellations and staged deployment strategies that evolve from regional to global coverage. This paper presents a two-part methodology for lunar navigation constellation design. First, a grid search systematically characterizes how the number of satellites and frozen orbit parameters influence the south-pole region and global coverage, orbit determination accuracy, and user range error, providing insights into orbit-performance trade-offs. Second, we introduce a staged-deployment optimization framework that jointly designs hybrid Walker constellations and deployment schedules across initial, extended, and full operational capability phases. The framework employs a novel metric—discounted weighted dilution of precision satisfaction ratio—that integrates geometric effects, user range error, and satellite failure probabilities. Simulation results demonstrate the ability to generate Pareto-optimal constellations that minimize satellite count while ensuring performance targets at each stage. This staged approach enables efficient constellation growth from regional to global service, offering insights for future lunar navigation infrastructure development.
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:	2836 - 2860
Cite this article:	Iiyama, Keidai, Gao, Grace, "Constellation Design and Staged Deployment for the Lunar Navigation Satellite System," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 2836-2860. https://doi.org/10.33012/2025.20257
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