Interplanetary Human Exploration Enabled by Lunar Swingbys and Libration-Point Orbits

Abstract

International collaboration will be necessary for a viable program of exploration beyond the Moon, similar to that for the ISS, and reusable spacecraft will also be needed. Highenergy Earth orbits that can be drastically modified with lunar swingbys and small propulsive maneuvers are used, especially near the collinear Sun-Earth and Earth-Moon libration points. The first human missions beyond low-Earth orbit may go to the vicinity of the translunar Earth-Moon libration point. This paper will concentrate on the next possible step, the first one into interplanetary space, that could be a one-year return mission to fly by a Near-Earth Object (NEO). Details are presented of a trajectory that leaves a halo orbit about the Earth-Moon L2 libration point, then uses three lunar swingbys and relatively small propulsive maneuvers to fly by the asteroid 1994 XL1, and return to the Earth-Moon L2 halo orbit for a V of only 432 m/s. Next, rendezvous missions to some other NEO’s will be presented. Finally, trajectories to reach Mars, first to Phobos or Deimos, will be outlined. The study uses highly-elliptical Earth orbits (HEOs) whose line of apsides can be rotated using lunar swingbys. The HEO provides a convenient and relatively fast location for rendezvous with crew, or to add propulsion or cargo modules, a technique that we call “Phasing Orbit Rendezvous”.