Lunar Lander Configurations Incorporating Accessibility, Mobility, and Centaur Cryogenic Propulsion Experience

Abstract

As part of the Vision for Space Exploration, NASA plans to develop a human lunar lander, known as the Lunar Surface Access Module (LSAM). A practical lunar lander must transport astronauts to the Moon, then facilitate their activities on the lunar surface. Propulsion systems using LO2/LH2 propellants have several advantages, including high specific impulse main propulsion, the opportunity for synergistic application in fuel cells and life support, and compatibility with In Situ Resource Utilization (ISRU). However, due to their very low boiling points, it is difficult to design systems which retain LO2 and LH2 for long mission durations. This paper describes design principles based on development and operational experience with the Centaur upper stage which can be applied to build practical LO2/LH2 lunar landers. These include the use of a minimum number of large propellant tanks with common bulkheads and thin-wall structure. Consideration has been given to crew and cargo operations on the lunar surface, which drive needs for lander mobility and ease of transfer between the lander cabin or cargo mounts and the ground. The low density of LH2 means that LO2/LH2 landers will have large fuel tanks which can impede crew access to the lunar surface. Three innovative design concepts are presented which incorporate the suggested propulsion design principles and address mobility and access. Concept 1 is a two-stage Dual Thrust Axis lander, which uses an axial main engine for primary descent, then rotates to land with its long axis parallel to the ground. As a result, the crew