Fully Safe Rendezvous Strategy in Cis-Lunar Space: Passive and Active Collision Avoidance

The future assembly of the Lunar Orbital Platform Gateway, on a near 9:2 resonant Rectilinear Halo Orbit, requires the necessity of designing safe and reliable strategies to perform rendezvous and docking with the station. The paper describes and tests a strategy to guarantee the safety of an entire rendezvous manoeuvre in the proximity of the Moon L2 Lagrangian point with respect to a specific set of failures. The safety in the far range is guaranteed through the automatic allocation of selected hold-points, whereas during close range rendezvous the safety is actively guaranteed in the presence of selected failures. The main goal of the paper is to contribute to the very limited literature about autonomous design of the guidance for rendezvous in presence of a non negligible third body influence, where safety considerations are paramount. The proposed approach is based on the exploitation of the manifold theory used in the circular restricted three body problem model to guarantee the passive safety in the far-range section, and on an optimal and reliable active collision avoidance manoeuvre to guarantee the safety for the close range approach.