Study on Displaced Orbits Below the Moon’s South Pole Near L2 Point Based on Solar Sail

This work explores displaced orbits of solar sails below the Moon’s south pole, near the L2 libration point in the Earth-Moon system. Light pressure provides acceleration for displaced orbits. These orbits enable continuous communication and observation of the Moon’s south polar region, where a lunar base is planned. Linearized dynamic equations yield analytical solutions of displaced orbits, which are either quasi-periodic or periodic. Quasi-periodic orbits have varying altitudes of hundreds of kilometers and a period of about a year, while periodic orbits have fixed altitudes аnd the same period. A sliding mode controller maintains the orbits using sail attitude angles and reflectivity as control variables. With a reflective area to mass ratio of 18 m2/kg, the displaced heights of quasiperiodic and periodic orbits near L2 are 2010.38 km and 2210.06 km, respectively. Numerical simulations confirm the controller’s effectiveness for both orbit types