Project Loop: A Sustainable Lunar Settlement Model by Sealing and Inhabiting a Lava Tube

Project Loop proposes a pioneering model for lunar settlement, transforming a lava tube into an expansive, pressurized habitat that protects against the harsh surface environment while supporting long-term human life. The project was awarded first prize in the Moon Station Competition promoted by YAC and ESA Topical Team on Planetary Caves. The Artemis program marks the beginning of a new era of lunar exploration, yet hostile conditions of the Moon present significant challenges to permanent colonization. Innovative approaches could reconceptualize the lunar environment, from an obstacle into a resource for human presence. Lunar lava tubes, natural underground channels formed by volcanic activity, represent a promising direction, offering stable temperatures and extensive protected space against radiation and micrometeoroids. Project Loop envisions a lunar lava tube base featuring a multifunctional architecture: a 3D-printed ISRU-based ring that acts as a habitable structure and operational infrastructure. Positioned at the tube entrance, this construction seals the underground cavity with a polymer composite membrane over its hole. Addressing both technical and habitability related challenges, the ring structure is designed in layers. It integrates pressurized primary functions such as laboratories and dormitories with a Bioregenerative Life Support System (BLSS) that recycles air, water, and waste. Moreover, the ring ensures safety redundancy with multiple airlocks and provides artificial lighting. Including a robust pressurization system, the ring will also gradually pressurize the lava tube itself, expanding the base into a wide underground environment, fostering a lunar urbanity. This approach enables a Closed Ecological System (CES) that improves long-term habitability, mitigating psychological challenges of confinement with a subterranean landscape and supporting large-scale lunar agriculture for food production. The model proposed by Project Loop could ensure a resilient lunar presence while offering a scalable framework for Mars and beyond. Furthermore, it could transfer sustainability approaches from space to Earth.