Accuracy Evaluation of Multi-Layer Lunar Navigation Satellite System: Reduction of PNT Convergence Time

Masaya Murata, Kyohei Akiyama, and Kota Tanabe

Peer Reviewed

Abstract:	This paper shows the effectiveness of the multi-layer lunar navigation satellite system (LNSS) in reducing the lunar PNT convergence time. In our previous papers, we proposed our baseline LNSS constellation using two stable moon orbits called the Elliptical Lunar Frozen Orbits (ELFOs) whose orbital periods were about 13 hours. Our LNSS was designed to provide the high-accurate PNT service at the lunar South Pole (SP) region. This baseline LNSS was composed of eight navigation satellites, four in each ELFO. On the other hand, in the field of the Low Earth Orbit (LEO) PNT, we are now observing the significant convergence time reduction of the Precise Point Positioning (PPP) for Earth users by augmenting the existing GNSS in Middle Earth Orbit (MEO) with many navigation satellites to be deployed in the LEO. Such a significant convergence time reduction could be achieved because the LEO navigation satellites move much faster than the GNSS satellites in the MEO and the measurement (temporal) diversity is achieved. This is one of the important features of the multi-layer GNSS (LEO PNT augmentation for the GNSS). In this paper, we evaluate the similar multi-layer LNSS concept to investigate the convergence time reduction of the lunar PNT. To do so, we augment our baseline LNSS constellation with a lunar polar orbit whose orbital period is 6 hours. This orbital period is about half of the orbital periods of our baseline ELFOs and the navigation satellites in this lunar polar orbit moves faster than those in the ELFOs. Using this multi-layer LNSS constellation, we evaluated how much convergence time reduction could be achieved for the lunar PNT, expecting the similar convergence time reduction to what the multi-layer GNSS (LEO PNT augmentation) could provide for Earth users. To the best of our knowledge, this is the first evaluation attempt to address such a multi-layer LNSS approach for the lunar PNT convergence time reduction and our evaluation results provided in this paper show the successful convergence time reduction.
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:	2878 - 2884
Cite this article:	Murata, Masaya, Akiyama, Kyohei, Tanabe, Kota, "Accuracy Evaluation of Multi-Layer Lunar Navigation Satellite System: Reduction of PNT Convergence Time," Proceedings of the 38th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2025), Baltimore, Maryland, September 2025, pp. 2878-2884. https://doi.org/10.33012/2025.20259
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