LUNAR CYCLER ORBITS WITH ALTERNATING SEMI-MONTHLY TRANSFER WINDOWS

This paper is a presentation of a new type of cislunar transfer orbit that has encounters with the Moon twice per month every other month. T he use of this technique is suggested for Earth-to-Moon Cycler spacecr aft that contain the heavy and expensive life support equipment for hu man transfer from low Earth orbit to the Moon and for logistical suppl y of lunar bases. The basis for the technique is a 180-degrees near-ci rcular Moon-to-Moon transfer orbit that is inclined to the Earth-Moon plane by an angle that is compatible with a low-inclination, near-mini mal energy Earth-to-Moon transfer orbit. Also included are preliminary discussions of Cycler spacecraft logistics for extensive manned opera tions on the Moon. Numerical studies are included to verify the useful ness of the technique in a realistic cislunar dynamic environment and estimates of navigation propellant requirements are given.