The classification of cislunar trajectories and its applications in the Earth–Moon system

This paper considers the evolvement of cislunar transfers and addresses two distinct types, i.e., direct and low-energy transfers based on Apollo and SMART-1 missions. Both direct and low-energy trajectories are discussed systematically in the context of restricted three-body dynamics in this paper. The differences between them are assessed by considering Jacobi energy and time of flight. Poincaré mapping is utilized to obtain the feasible cislunar trajectories and to demonstrate the relationship between Jacobi energy, perilune or perigee radius and the characteristics of cislunar trajectories such as time of flight, the two-body energy with respect to the Moon at perilune. Several laws, which illustrate the relationships between Jacobi energy, perilune or perigee radius and the characteristics of cislunar trajectories such as time of flight or minimum time of flight, are concluded. Moreover, global sketches are accomplished to present the distribution of low-energy and direct cislunar transfers as well as specific transfers including resonance cyclers, also revealing the evolvement of cislunar transfers through the relationship between Jacobi energy, and perilune/perigee. Finally, applications in geosynchronous orbit deorbiting and lunar relay satellite system are put forward.