Three-maneuver transfers from the cislunar L2 halo orbits to low lunar orbits

Abstract

In this paper, a three-maneuver strategy is presented to study the transfer from a cislunar L 2 halo orbit to a low lunar orbit (LLO). Both the cislunar L 2 point orbits and lunar orbits are generally considered as habitats for space vehicles of various missions, so a transfer strategy between these orbits that combines flexibility with minimal fuel consumption is worth considering for future complex space applications in the Earth-Moon system. In terms of the three-maneuver transfer method, the first maneuver is carried out along the direction of the unstable invariant manifold toward the moon, and each point in the halo orbit can be a departure position of the transfer. Then, the spacecraft is allowed to drift for a period of time, but in the meantime we are constantly searching the window for the second maneuver that towards the target LLO and figuring out the transfer trajectory for optimal maneuver cost. The third maneuver is a deceleration into the target LLO. The transfer procedure is first established in the circular restricted three-body problem (CRTBP) model, with a feasibility analysis of not constraining orbital inclination of LLOs. After that, the results of the transfer to both polar and equatorial LLOs in the CRTBP model are used as initial solutions for the design procedure of transfer trajectories in the ephemeris model. Finally, optimized results of transfer window of up to 180 days with corresponding overall maneuver costs in the ephemeris model are given for a quasi-halo orbit, which demonstrate the flexibility and reliability of the three-maneuver transfer strategy.