Multi-objective optimization of lunar communication/navigation constellations based on LPOs and DROs

In the last years, lunar exploration has aroused great interest of the public again. Many countries and space agencies have developed an increasing number of lunar missions. These missions demand increasing communication and navigation services for both on-ground and in-flight users. Therefore, it is necessary to deploy constellations around the moon with appropriate functions. Libration point orbits (LPOs) and distant retrograde orbits (DROs) in the Earth-Moon system are extensively studied by researchers for lunar constellations. They can cover a wider lunar surface than conventional Kepler orbits and can easily achieve continuous coverage of some specific regions, such as the far side of the moon. In previous studies, constellations using these orbits were not optimized or only optimized within limitations. Generally, the phases of satellites were not optimized together with other parameters because this can significantly increase the amount of calculation. This will result in missing many solutions with good performances. In this study, a multi-objective optimization (MOO) framework for lunar constellation design is proposed. It significantly reduces computation by preprocessing the orbits and building a database. Relevant performances of constellations, such as the coverage, navigation precision, and orbital stability, are identified. Then, they are mapped to different regions of interest, including the lunar south pole, far side, whole moon surface, and their combinations. Finally, a MOO algorithm is used to retrieve optimal orbital architectures of constellations for various expected performances. This framework can be used to explore the entire design space and make balances between various performances. The obtained constellations can provide specialized communication and navigation services for various lunar exploration missions in the future.