Filipe Pereira, Cornell University; Daniel Selva, Texas A&M

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Abstract:

The gradual expansion of infrastructure on and around the Moon is key to establishing the long-term exploration of the Moon through e.g., NASA’s Artemis and Commercial Lunar Payload service missions. Current missions are largely dependent on the support of the Deep Space Network (DSN) for communication and navigation services at lunar distances. The future increase in demand for these services is likely to be beyond the capabilities of the DSN, which is operating close to capacity. Despite recent work showing that Earthbound Global Navigation Satellite System (GNSS) signals can be received at lunar distances, these signals are mostly relevant for time synchronization, since the poor Dilution of Precision (DOP) severely limits their usefulness for precise navigation purposes. In this work, we analyze the navigation performance of two 24-satellite Lunar GNSS constellations. The first architecture was identified in a previous study, using a multi-objective evolutionary optimization framework. It consists of a Walker constellation in near-circular polar orbits at an altitude of ~2 lunar radii that requires modest station-keeping deltaV. The second architecture is based on eccentric repeat ground-track orbits that are shown to have long-term stability and are similar to other architectures proposed in the literature. It is shown that the ISECG absolute positioning goal of 40cm can be achieved by a sub-constellation of architecture 1 with at least 16 satellites if pseudorange and delta range measurements are used. The economic analysis shows that a 16-satellite sub-constellation of architecture 1 can outperform the 24-satellite constellation of architecture 2 while being deployed at a similar cost. an 8-satellite Lunar GNSS constellation would outperform the position accuracy of DSN tracking assuming one 8-hour pass/day. It is estimated that the cost of an 8- satellite Lunar GNSS constellation could be amortized in 15 years by DSN tracking cost savings alone.