Bearings-only Guidance for Rendezvous in a Cis-lunar NRHO

The current plans of returning to the Moon involve rendezvous and docking/berthing with the Lunar Gateway, whose targeted orbit is a Near Rectilinear Halo Orbit. In this work, a guidance algorithm for the close-range rendezvous phase of the proposed lunar sample return mission HERACLES is designed, assuming the chaser can measure relative angles only to the target. The navigation performance is affected by the maneuvers performed because their execution is necessary to make the problem observable. The relative motion equations with third body perturbation are considered directly in the guidance algorithm, with the additional aim of improving observability during the approach trajectory.