Entry System Options for Human Return from the Moon and Mars

Earth-entry system options for human return missions from the moon and Mars were analyzed and compared to identify trends among the configurations and trajectory options and to facilitate informed decision-making at the exploration architecture level. Entry system options included ballistic, lifting capsule, biconic, and lifting body configurations with direct-entry and aerocapture trajectories. For each configuration and trajectory option, the thermal environment, deceleration environment, crossrange and downrange performance, and entry corridor were assessed. In addition, the feasibility of a common vehicle for lunar and Mars return was investigated. The results show that a low lift-to-drag ratio (L=D   0:3) vehicle provides sufficient performance for both lunar and Mars return missions while providing the following benefits: excellent packaging efficiency, low structural and thermal protection system mass fraction, ease of launch vehicle integration, and system elegance and simplicity. Numerous configuration options exist that achieve this lift-to-drag ratio.