Strategies and Applications for Sustained Multi-Vehicle Loitering in the Gateway NRHO

NASA's Gateway plans to operate in an L2 Near Rectilinear Halo Orbit (NRHO) near the Moon for nominal operations. During the mission's lifetime, various visiting vehicles may need to loiter on an alternate trajectory for a considerable amount of time. This investigation examines various strategies and configurations for visiting vehicles loitering near the Gateway. Characteristics of loitering in a string of pearls or quasi-periodic orbit configuration in the ephemeris model are investigated with consideration of operational errors. For sustained loitering in the NRHO, modifications to orbit maintenance strategies are discussed. Additionally, variations from predicted baseline trajectories are examined to understand the impacts for an as-flown spacecraft.