ECLIPSE: Design of a Minimum Functional Habitat for Initial Lunar Exploration

In the fall of 2008, NASA awarded a series of competed contracts for six different technologies related to lunar exploration. The topic most represented, with three awards, was for the design of a minimum functional habitat. One of the three awards went to the University of Maryland Space Systems Laboratory (SSL). This paper summarizes the results of ECLIPSE: the Extensible Concept for Live-In Pressurized Sortie Elements. As per the top-level requirements, ECLIPSE was designed to be a minimum functionality habitat: no features were to be incorporated unless required for crew safety, minimum habitability, or basic functionality. The initial stages of the study incorporated literature reviews and regression analysis, surveys of critical habitation elements from a population experienced in seaboard, Arctic, Antarctic, and space habitats, multiple preliminary designs, and parametric analysis of habitat mass and habitable areas. This effort allowed the selection of an optimal two-level vertical habitat configuration for a detailed design analysis, as documented in this paper. Based on a vertical cylinder with a diameter of 3.65 m and a height of 5.5 m, the final design provides personal sleeping berths and stowage for each of the four crew, which double as a storm cellar in the event of a solar particle event. The upper deck of the ECLIPSE habitat incorporates facilities for sleeping, food preparation, eating, and sanitary facilities, while the lower floor is devoted to operations. Four suitports are provided to allow extensive lunar surface suited operations without contaminating the habitat with regolith; an inflatable airlock is also provided for occasions where suits need to be brought inside for maintenance and servicing. Three berthing ports at 120o angles allow the interconnection of multiple ECLIPSE modules to build up a more elaborate outpost habitat for larger crews or more extended stays, and are compatible with NASA surface architecture elements such as pressurized logistics modules. Full specifications were developed for all necessary life support, thermal control, and avionics systems. Unique to this design was a strong focus from the outset on stowage; the ECLIPSE design provides a total internal stowage volume of 5 m3 . To assess the functionality of the selected design, a full-scale mockup was fabricated, assembled, and tested in parallel with the final habitat design. Fitted out with full accommodations including water, food preparation, and sanitary facilities, the mockup was used to assess habitability issues, culminating in a four-person multiday habitation experiment. This experience provided a great deal of information about the final design. While it did verify the functionality of the multideck habitat in a tightly constrained volume, it provided several cautionary experiences which were incorporated into the final design. Although the actual NASA contract was limited to a six-month duration, the University of Maryland intends to continue and extend the ECLIPSE concept, through both additional CAD-based design and further simulation activities in the full-scale mockup. Future plans include the incorporation of a small pressurized rover mockup to examine synergies between heterogenous small habitable systems, and greater detail on the requirements for a habitat in support of lunar surface operations.