Novel Solar-Sail Mission Concepts for High-Latitude Earth and Lunar Observation

Solar-sail periodic orbits in the Earth-moon circular restricted three-body problem are proposed for continuous observation of the polar regions of the Earth and the moon. The existence of families of solar-sail periodic orbits in the Earth-moon system has previously been demonstrated by the authors and is expanded by introducing additional orbit families. Orbits for near-term solar-sail technology originate by maintaining the solar sail at a constant attitude with respect to the sun such that mission operations are greatly simplified. The results of this investigation include a constellation of two solar-sail L-2-vertical Lyapunov orbits that achieves continuous observation of both the lunar South Pole and the center of the Aitken Basin at a minimum elevation of 15deg. At Earth, a set of two, clover-shaped orbits can provide continuous coverage of one of the Earth's poles at a minimum elevation of 20deg. Results generated in the Earth-moon circular restricted three-body model are easily transitioned to one that includes eccentricity effects and demonstrates that the orbits are feasible in realistic regimes.