Research on Lunar Navigation Satellite System (LNSS)
Period: 2019/4 - Present
The Lunar Navigation Satellite System (LGSS) could significantly improve lunar missions’ operational capability and flexibility by providing real-time, continuous, and highly accurate positioning services to lunar users. Research topics that I have been working on are listed below.
1. LNSS Simulator Development and Configuration Optimization
The research aims to obtain optimal configuration (e.g., arrangement of navigation satellite and lunar monitoring station) that could minimize cost while achieving the required performance. I developed an LNSS simulator and an optimizer to tackle this problem.
Previous studies have shown that the required number of navigation satellites to cover the entire lunar surface could be reduced by deploying them on Halo Orbits. My undergraduate research demonstrated that the global positioning performance could be improved by deploying satellites on two stable periodic orbits: Distant Retrograde Orbits (DROs) and Near Rectlinear Halo Orbits (NRHOs).
Related Publications:
- Iiyama, K., “Optimization of the Navigation satellite constellation and Lunar Monitoring Station for Lunar Global Navigation Satellite System”, 32nd International Symposium on Space Technology and Science, Fukui, Japan, 2019 [paper]
2. Autonomously Operated Networked Navigation Architecture
The development of a robust navigation infrastructure in cis-lunar space is crucial for the coming new era of advanced lunar exploration. NASA has set a goal to develop an extensible and scalable lunar communication, and navigation architecture called LunaNet. For the flexibility and robustness of the system, the architecture is desired to have an autonomous and decentralized operation capability. In this work, we propose a decentralized and autonomous state estimation algorithm for SmallSats that provides positioning, navigation, and timing service, each equipped with a GNSS receiver, a chip-scale atomic clock, and a steering antenna for inter-satellite communication. In our framework, each satellite individually estimates its own state and clock offset with a modified decentralized Schmidt Extended Kalman Filter by processing weak GNSS signal and inter-satellite range measurements. We also demonstrate that by deploying a total of 5 satellites on lunar frozen orbit and halo orbit, the PNT service area could be extended to regions where direct GNSS signals are not available, including the far side and pole regions of the moon.
Related Publications: