Exploration of distant retrograde orbits around Moon

This paper deals with the cislunar transfer problem. A new type of distant retrograde orbit (DRO) is proposed and its stability is investigated. The Lyapunov orbits tangential to the retrograde orbit are applied to design the entry of transfer trajectories, i.e., the invariant manifolds of Lyapunov orbit around L₁ are applied to achieve the quick transfer to DRO, meanwhile the Lyapunov orbit around L₂ is used as the entrance to weak stability boundary (WSB) transfer, so that the low energy transfer to DRO is achieved. The numerical simulations is given to validated the feasibility of the two transfer modes.