Low Energy Trajectories for the Moon-to-Earth Space Flight
The Moon-to-Earth low energy trajectories of “detour” type are found and studied in frame of the Moon-Earth-Sun-particle system. These trajectories use a passive flight to the Earth from an initial elliptic selenocentric orbit with a high aposelenium. The Earth perturbation increases the particle selenocentric energy from a negative value first to zero and then to a positive one and therefore leads to a passive escape of the particle motion from the Moon attraction near the translunar libration point L2. This results in the particle flight to a distance of about 1.5 million km from the Earth where the Sun gravitation decreases the particle orbit perigee distance to a small value that leads to the particle approach the Earth vicinity in about 100 days of the flight. A set of the Moon-to-Earth “detour” trajectories is defined numerically. Characteristics of these trajectories are presented. The ”detour” trajectories give essential economy of energy (about 150 m/s in Delta V) relative to the usual ones.