Iac-05-c1.6.01 Transfers between the Earth-moon and Sun-earth Systems Using Manifolds and Transit Orbits

The L1 and L2 libration points have been proposed as gateways granting inexpensive access to interplanetary space. The lunar libration points, in conjunction with the collinear libration points in the Sun-Earth system, may also become primary hubs for future human activities in the Earth’s neighborhood. The associated manifold tubes have been introduced by a number of researchers as the basis for design strategies to produce trajectories that shift between different systems. Intersections may ultimately be sought between many tubes from many different libration point orbits in each system; the complexity forces a new look at the computations. Individual transfers between three-body systems have been the focus of some recent investigations. This paper presents an approach to solve the general problem for transfers between the Earth-Moon system (lunar orbits and/or lunar libration point orbits) and Sun-Earth/Moon L2 libration point orbits. The solutions are transitioned to the full ephemeris models with additional perturbations and the transfers can be determined for various lunar phases. The solution process also seeks the particular Lissajous trajectory in each system to accomplish the transfer at a low cost. Some results are presented for various types of transfer problems. INTRODUCTION After numerous successful missions involving Sun-Earth libration point orbits, the design potential in multi-body regimes has generated great interest. For example, the lunar libration points, in conjunction with the collinear libration points in the Sun-Earth system, could become primary hubs for future human activities in the Earth’s neighborhood. Large astronomical observatories will likely be located near the Sun Earth L2 point requiring human servicing and repair. The Earth-Moon L1 libration point is suggested as a possible staging node for missions to the Sun-Earth L2 point as well as the Moon, Mars, and the rest of the solar system. Thus, the L1 and L2 libration points have also been proposed as gateways granting inexpensive access to interplanetary space. Libration point orbits in other three-body systems might also facilitate understanding of the structure of the solar system and the design of low energy transfers throughout interplanetary space. As the possibilities expand, it becomes essential to further develop efficient numerical tools for analysis and design in such multi-body regimes. Halo orbits and invariant manifolds are now well-known dynamical structures in this region of space and have been employed as tools to design various types of transfers and spacecraft trajectories. But, the complexity is increasing. For near-term plans in the Earth’s neighborhood, numerous proposals for infrastructure as well as exploratory and scientific missions involve spacecraft moving freely throughout the local