Orbit Maintenance Burn Details for Spacecraft in a Near Rectilinear Halo Orbit

The baseline orbit for Gateway is a Near Rectilinear Halo Orbit (NRHO) in a 9:2 resonance with the lunar synodic period. A spacecraft in this slightly unstable NRHO requires orbit maintenance (OM) for long-duration operations. An updated OM algorithm is described, including a discussion of desirable OM burn location along the NRHO and the effects of changing weighting parameters and tolerances. The directions of the OM burns are explored in depth, both in the Earth-Moon rotating frame and from a Sun-relative perspective. A technique to augment the OM algorithm to enable long-term operations in NRHO is outlined, and the effects of constraints on OM attitudes are investigated.