Optimal Low-Thrust Earth and Planetary Transfers

Mixed low-thrust invariant-manifold transfers to Mars

Low-thrust transfers applied over long periods of time permit significant fuel savings as well as other benefits, such as closed-loop implementation, implying low sensitivity to disturbances compared to open-loop optimal trajectories previously conceived. Based on Gauss's variational equations, we have previously demonstrated the accessibility of the low-thrust orbit transfer from any initial Keplerian orbit to almost all desired target orbits. Low-thrust transfers include simple guidance schemes, or multi-objective optimization-based algorithms aimed at selecting the parameters of a Lyapunov feedback control law, used in most closed-loop guidance schemes. The main goal of this work is to design LEO-to-GEO low-thrust orbital transfers under space debris constraints and to infer how space debris affect the geometry of low-thrust orbital transfers. The tools and techniques are also applied to planetary transfers.