Design of Earth-Moon L2 Halo Orbit Transfer Trajectory for Relay Satellite Using Lunar Flybys

The satellite on Earth-Moon L2 periodic orbit will provide communication relay for CE-4，China’s first Lunar landing exploration mission on the moon’s far side. The transfer orbit design plays an important role in the implementation of the relay mission. Considering the constrains on transfer time，flyby altitude and amplitude of the halo orbits，this paper systematically studies the Earth-Moon L2 transfer trajectory using Lunar flybys. First，based on the restricted three-body problem（RTBP），the visibility of the landing point with different families of halo orbits is analyzed. Then，the transfer orbit is divided into Earth-Moon direct transfer segment and quasi manifolds associated with halo orbits. The differential correction algorithm with state constraints is employed to match the two segments. Finally，aiming at southern family of halo orbits，the influence of orbit amplitude and Lunar flyby altitude on the cost of transfer as well as orbit insertion phase are discussed respectively. The simulation shows the feasibility and engineering advantages of lunar flyby transfer.