IMPROVING VEHICLE REUSABILITY FOR HUMAN EXPLORATION OF NEAR-EARTH ASTEROIDS USING SUN-EARTH LIBRATION POINT ORBITS

摘要

Current plans for human exploration of the solar system envision several missionsto Near-Earth Asteroids (NEAs) as stepping stones towards missions to Mars. Thisresearch investigates the feasibility of stationing reusable cargo spacecraft, such ashabitats, in halo orbits at Sun-Earth Libration points 1 and 2 (L1 and L2) betweenNEA missions in an effort to reduce mission cost and thus overall campaign costby lowering the mass required to be launched and the amount of new hardware tobe built for each mission. Four example missions to the two currently most promisingtargets of the known NEA population in the 2025-2030 time frame are chosen.In the mission architecture proposed in this study, the crew vehicle directly commutesbetween Earth and the asteroid in order to keep mission durations for thecrew short. The cargo vehicle departs from a halo orbit, rendezvous with the crewvehicle on the outbound trajectory, and returns to a halo orbit after the mission.Manifold trajectories of halo orbits in the northern and southern halo orbit familyat L1 and L2 are considered for the transfer of the cargo vehicle to and from theinterplanetary trajectory and the total Δv required for this transfer is minimized.This Δv is found to range from a few meters per second to hundreds of metersper second, depending on the specific energy and inclination of the interplanetarytrajectory. These results show the great potential of the utilization of Sun-Earthlibration point orbits for enabling vehicle reusability, thus lowering the cost ofhuman exploration missions.