Operations-Driven Strategy for Safely Approaching the Lunar Gateway Throughout Its Orbit

Cislunar stations in near-rectilinear halo orbit (NRHO), like the Lunar Gateway, once a part of NASA’s Artemis program architecture, pose a unique challenge for rendezvous and proximity operations. The dynamics of this orbit vary greatly over each revolution, and currently developed strategies limit approaches to a region centered on the orbit’s apolune. This work proposes an approach strategy for operators to reference as they navigate their visiting vehicle from outside Gateway’s rendezvous sphere to just outside its keep-out sphere. The strategy is composed of sets of nominal and contingent strategies predicated on Gateway’s positioning within the NRHO. The proposed strategies are prescribed for all dynamic regions of the NRHO, enabling approaches in time-critical scenarios where operators cannot wait for a particular Gateway orbital alignment. Approach trajectories, developed in a circular restricted three-body problem (CR3BP) model, are designed to maintain visiting vehicle safety in accordance with proposed flight rules while ensuring that selected trajectories are [Formula: see text] efficient. A graphical reference for the complete strategy is presented alongside nominal and off-nominal approach scenarios, demonstrating how the strategy could be executed in a real mission.