Asteroid Observation and Landing Trajectories Using Invariant Manifolds

In this paper a study of the equilibrium points of a rotating non-spherical asteroid is performed with special emphasis on the equilibria aligned with the longest axis of the body. These equilibrium points have the same spectral behaviour as the collinear Lagrange points of the Restricted Three Body Problem (RTBP), saddle-centres, and therefore unstable and stable invariant manifolds can be computed. The invariant manifolds of the equilibrium point or periodic orbits around it, which are fuel-free trajectories, can approach the surface of the asteroid, orbit around it for di�erent amounts of time, and even impact on it. This paper studies the dependence of the existence of fuel-free trajectories to the surface of the asteroid from the equilibrium point on the shape and rotation rate of the body. A possible manoeuvre to orbit the asteroid to observe it and later achieve vertical landing is proposed. The theory developed is then applied to asteroid 4660 Nereus, for which an approach, observation phase and landing manoeuvre is designed