Modeling and Design of a Communication and Navigation Satellite Constellation for the Lunar South Pole

摘要

Exploration architectures for lunar surface and lunar orbit exploration have been widely considered in the past with increased interest and attention since the Constellation program of the previous decade. Communication requirements for those architectures have figured prominently in analyses of both mission performance and mission safety. In this study, a comparison is made of architectures proposed as potential alternatives to that of NASA's Space Communication Architecture Working Group (SCAWG) with a focus on safety/redundancy requirements for future space exploration. The approach of this study focuses on satellites in 'frozen-orbits' as proposed by previous researchers. These orbits are selected to optimize (reduce) propellant consumption to maintain the orbit and associated coverage. The constellation of satellites provides an opportunity to minimize the number of satellites while maintaining redundancy in order to achieve fault tolerance to future exploration missions which depend on the continued operation of the satellites. To consider coverage, this investigation selects Shackleton Crater, near the Lunar South Pole, as the primary destination. Secondary targets for analysis are Orientate 1 and Peary crater. This study shows that nearly continuous single coverage is achieved for the South Pole with majority time single fault tolerance (double coverage) for a highly elliptical and inclined three satellite constellation. By comparison, a near-circular and less inclined three satellite constellation gives geographically broader but less concentrated (redundant) coverage for the site of primary interest.