Lunar relay satellite capabilities via re-use of delivery vehicle modules

Lunar communications can be problematic for mission success when trading multiple objectives such as reduced mass, landing trajectory, and the need for communication with other orbiting vehicles and ground stations. To this end, reusability of existing vehicle components - for purposes other than the original intent - is an enticing option. In the case of Constellation, the Ares upper stage instrument unit avionics IUA has promise for re-use as a lunar relay satellite. The guidance, navigation and control GNC avionics along with the electrical power system can be re-used to position the IUA into a suitable lunar orbit for use as a relay. The IUA can be inserted into a medium lunar orbit via re-use of the earth departure stage EDS for the lunar orbit insertion LOI burn. Additionally, the descent module from the Altair can be re-used as either a beacon on the lunar surface or as a relay node for surface operations. The ascent module can be reconfigured and reused as an orbiting relay satellite. The re-use of these modules would greatly improve the effective delivered mass. This specific instance of re-use improves the following mission objectives a) enhanced safety via improved situational awareness, b) increased public visibility of NASA's lunar mission, and c) higher volume of data for scientific discovery. We present an architecture for re-use of modules to populate a lunar communications satellite system.