Optimal Launch Vehicle Size Determination for Moon-Mars Transportation Architectures

NASA’s human Lunar and Mars exploration (HLE/HME) program requires a sustainable and affordable transportation system between Earth and Moon/Mars. A crucial element of this system is the launch vehicle. Much debate has centered on the trade between expendable launch vehicles and heavy-lifters; however, arguments to date have been largely qualitative or limited in scope. This paper provides a quantitative enumeration of the launch vehicle trade space (in terms of both cost and risk), based on a generalizable process for generating launch manifests from transportation architectures (sets of vehicles for carrying out Lunar/Mars missions). For the baseline HLE/HME architecture considered here, an optimal launch vehicle size is found at approximately 82 metric tons; a 28-mt EELV emerges as another good option. The results show optimal launch vehicle selection is highly dependent on the transportation architecture. Therefore, launch vehicle selection should be considered an integral part of the design of the Moon/Mars exploration transportation system.