Low Energy, Low-Thrust Capture of Near Earth Objects in the Sun-Earth and Earth-Moon Restricted Three-Body Systems

摘要

In this paper a method to retrieve asteroids incorporating low-thrust propulsion into the invariant manifolds technique is investigated. Assuming that a tugboat-spacecraft is in a rendez-vous condition with the candidate Near Earth Object (NEO), the aim is to take the joint spacecraft-asteroid system to selected periodic orbits of the Earth-Moon restricted three-body system: the orbits can be either libration point periodic orbits (LPOs) or distant periodic orbits around the Moon, both prograde (DPOs) and retrograde (DROs). In detail, low-thrust propulsion is used to bring the joint spacecraft-asteroid system from the initial condition to a point belonging to the stable manifold associated to the final periodic orbit: from here onward, thanks to the intrinsic dynamics of the physical model adopted, the flight is purely ballistic. The idea is to couple together the Sun-Earth and the Earth-Moon models following the "patched restricted three-body problems approximation", therefore allowing the spacecraft-asteroid system to fly along the interplanetary manifold trajectories, explicitly exploiting the hyperbolic transit orbits flying by L_1 and L_2. Dedicated capture sets are introduced to exploit the combined use of low-thrust propulsion with stable manifolds trajectories, aiming at defining feasible first guess solutions. An optimal control problem is then formulated to refine them. This approach enables a new class of missions, whose solutions are not obtainable neither through the patched-conics method nor through the classic invariant manifolds technique.