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

Abstract

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 L1 and L2. 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.