Lunar Sunrise Orbits and Applications to NASA CLPS Missions

NASA’s Commercial Lunar Payload Services (CLPS) initiative has stimulated the lunar economy with recent and planned landings on the Moon by U.S. companies. The primary purpose of this paper is to define, discover, and analyze Lunar Sunrise Orbits (LSOs), sun-synchronous and near repeat ground orbits at the Moon that are phased for a spacecraft to encounter a landing site at sunrise. This unique class of orbits can be used as a nominal staging orbit for future CLPS lunar lander missions to provide backup landing opportunities at lunar sunrise. An LSO reference orbit adds mission resiliency and robustness without any propellant cost in the case of a missed descent maneuver in low lunar orbit. Classical lunar frozen orbits will also be explored in the context of LSOs with applications shown for future CLPS missions and concepts.