Efficient invariant-manifold, low-thrust planar trajectories to the Moon

Two-impulse trajectories as well as mixed invariant-manifold, low-thrust efficient transfers to the Moon are discussed. Exterior trajectories executing ballistic lunar capture are formalized through the definition of special attainable sets. The coupled restricted three-body problems approximation is used to design appropriate first guesses for the subsequent optimization. The introduction of the Moon-perturbed Sun-Earth restricted four-body problem allows us to formalize the idea of ballistic escape from the Earth, and to take explicitly advantage of lunar fly-by. Accurate first guess solutions are optimized, through a direct method approach and multiple shooting technique.