An Evolvable Lunar Communication and Navigation Constellation Architecture

Abstract

NASA’s Global Exploration Strategy and proposed lunar architecture present a roadmap for future U.S. missions. Th e exploration plan begins with robotic precursor missions, followed by human sorties, eventually progressing to an outpost on the lunar surface near the South Pole. This location limits direct communication links with Earth. A lunar relay element will be n ecessary to provide critical communication and navigation support. This paper presents a highly evolvable, low -cost lunar relay constellation concept using small satellites in halo orbits about the Earth -Moon libration points L 1 and L 2. The initial constel lation is designed to provide coverage of the lunar South Pole in support of the inaugural robotic missions and is easily expanded to provide global coverage. Two satellites in an L 2 halo orbit provide continuous South Pole coverage for the initial constel lation. A final constellation providing nearly continuous global coverage can be achieved by the addition of two spacecraft in an L 1 halo orbit. A basic set of requirements and desired capabilities for the constellation is developed, based on NASA reports and Constellation C3I compatibility. A preliminary spacecraft bus and subsystems design is presented along with expected performance.