A comprehensive review of lunar lava tube base construction and field research on a potential Earth test site

The Moon, as the closest celestial body to the Earth, plays a pivotal role in the progression of deep space exploration, and the establishment of research outposts on its surface represents a crucial step in this mission. Lunar lava tubes are special underground caves formed by volcanic eruptions and are considered as ideal natural shelters and scientific laboratories for lunar base construction. This paper begins with an in-depth overview of the geological origins, exploration history, and distribution locations of lunar lava tubes. Subsequently, it delves into the presentation of four distinctive advantages and typical concepts for constructing bases within lava tubes, summarizing the ground-based attempts made thus far in lunar lava tube base construction. Field studies conducted on a lava tube in Hainan revealed rock compositions similar to those found during the Apollo missions and clear lava tube structures, making it a promising analog site. Lastly, the challenges and opportunities encountered in the field of geotechnical engineering regarding the establishment of lunar lava tube bases are discussed, encompassing cave exploration technologies, in-situ testing methods, geomechanical properties under lunar extreme environments, base design and structural stability assessment, excavation and reinforcement techniques, and simulated Earth-based lava tube base.