Long-Term Loitering Transfers in the Vicinity of a Near-Rectilinear Halo Orbit

Growing interest in cislunar space has motivated the study of orbits suitable for sustained lunar operations, among which the Earth–moon 9:2 [Formula: see text] southern near-rectilinear halo orbit (NRHO) has emerged as a key orbit of interest. Vehicles operating in the vicinity of this NRHO may perform rendezvous, proximity operations, and docking/undocking with assets in this orbit. As such, keeping vehicles safe while in the NRHO or in transit to and from the lunar surface is imperative. Uncrewed vehicles such as landing system support vehicles, resupply craft, or CubeSat deployments may remain in the vicinity of the NRHO during crewed missions. Due to operational constraints, certain visiting vehicles may need to enter a loitering configuration with a primary asset in the NRHO. Long-term loitering can be achieved by placing spacecraft in orbits in the vicinity of the NRHO. Established methods are applied to construct transfers to various locations near the 9:2 [Formula: see text] southern NRHO. These methods include leveraging dynamic systems techniques to construct initial guesses that inform a higher-fidelity analysis. Results demonstrate that the application of dynamic systems techniques yields cost-effective transfer options for manifold-based, direct, and low-thrust strategies.