Lunar Constellation of Frozen Elliptical Inclined Orbits

A document discusses the design of orbits of spacecraft for relaying communications between Earth stations and robotic and human explorers in craters in one of the polar regions on the Moon. In simplest terms, the basic problem is to design a constellation of orbits to provide continuous and preferably redundant communication coverage of one of the poles with a minimal number of spacecraft and little or no controlled maneuvering of the spacecraft to maintain the orbits. The design method involves the use of analytical techniques for initial selection of orbits, followed by a numerical procedure for tuning the coverage of the constellation to obtain a design. In an example application, the method leads to a constellation of three spacecraft having elliptical, inclined orbits, the apoapsides of which would remain in the hemisphere (North or South) containing the pole of interest. The orbits would be stable and would maintain the required spacecraft formation for at least 10 years, without need for controlled maneuvering if gravitation is the only force considered to affect the orbits. A small amount of controlled maneuvering would be needed to counteract effects of solar-radiation pressure and other perturbations.