Composite Structure Enabling an Efficient Lunar Surface Habitat

The establishment of sustainable habitats on the lunar surface is paramount for advancing human exploration and scientific endeavors beyond Earth and enables NASA's Sustained Lunar Evolution in the Moon to Mars Architecture. Such habitats require structural solutions that minimize delivered mass while maximizing volumetric efficiency, long term integrity, and mission operability. This paper delves into the innovative design of an all composite Lunar Surface Habitat (LSH), replicating Boeing’s proven composite design, analysis, and build capability but extending it into a novel system level application: a continuous, joint minimized carbon fiber reinforced polymer (CFRP) pressure shell layup that constitutes the primary structure for a crewed habitat. The innovation is both material and architectural — an integrated, all composite habitat concept that has not previously been implemented for habitable space modules.

The study was conducted under NASA’s NextSTEP-2 Appendix A. One of the key focuses of this study was the composite primary structure of the LSH, which constitutes only 17% of the total mission mass compared to typical module’s structure comprising 25%-50% of the total mass. This remarkable weight reduction is achieved using carbon fiber reinforced polymer laminate, which offer a high strength-to-weight ratio essential for space applications. The lightweight nature of the composite structure not only facilitates the launch, landing, and transportation of the habitat but also enhances the module’s overall performance by redeploying structural mass allocation to other functions, thereby increasing mission capability or reducing risks.

A significant advantage of utilizing composite structures is the expanded design space it affords. The reduced mass and flexible manufacturing of the composite primary structure enables the development of an innovative two-story module. This design not only maximizes the use of internal volume but also strategically locates hatches low to the lunar surface, facilitating easier ingress and egress for crew members during extravehicular activities (EVAs) and the mating of pressurized vehicles to its port. The two-story layout allows for a clear separation of functional areas, enhancing operational efficiency and crew comfort.

The paper details how all the defined Ground Rules and Assumptions (GRAs) were met or exceeded for a four crew, 30 day mission. Chief among the Ground Rules was the mass target, which was met by implementing very efficient structure and by a deferred items approach where equipment is brought up and installed on the first mission via a pressured logistics carrier.

The findings underscore the potential of composite technology to revolutionize habitat construction for deep space applications. The successful implementation of a lightweight composite primary structure not only enhances the feasibility of lunar habitation but also sets a precedent for future missions to Mars and beyond. The study demonstrates that the strategic use of composite materials in the LSH design significantly contributes to the mission's success by optimizing mass, enhancing structural performance, and enabling innovative configurations that improve crew operations.