On the Optimal Extension of Ground Network Stations to Support NASA´s Lunar Exploration

NASA´s vision for space exploration is to establish a permanent human presence on the Moon beginning no later than 2020. Its initial base is centered at the lunar south pole and its subsequent sorties and outposts could practically be anywhere on the lunar surface, including the far side. From time to time, there will be a crew exploration vehicle at the Moon exchanging astronauts using a lunar surface access module. It is also proposed to deliver one to two lunar relay satellites to the Moon to increase the connectivity between the Earth ground stations and the users on or near the Moon as well as to alleviate the lunar spacecraft burdens, such as mass and power. As a result, there will be critical periods when multiple spacecrafts at the Moon require simultaneous coverage.