Stability Analysis of Lunar Lava Tubes for Permanent Extraterrestrial Habitation

摘要

Lunar lava tubes are natural tunnels under the Moon surface that form when the liquid lava continues to flow underneath a cooled lava crust. The lunar lava tubes can provide a long-term shelter against hazards such as meteorite impacts, cosmic radiation and temperature fluctuations. Their existence is suggested by images taken of vertical holes "skylights" by the LRO and SELENE spacecraft, and is further supported by gravity data from the GRAIL mission. The GRAIL data suggested that lava tubes can be 1000-2000 m wide and several hundred kilometers long, much larger than the terrestrial analogs (10-30 m wide). In this study, we use the lava flow characteristics and limit equilibrium analysis of the collapsed skylights to investigate the cross-section size of lunar lava tubes. The structural stability of the tubes with different geometries and material properties is analyzed using the finite element method code ABAQUS. Our analyses show that: a) the existence of lava tubes ~1000 m wide is possible; b) the roof thickness and strength of the basaltic rock, particularly the tensile strength, are the key parameters defining stability; c) for a 1000 m wide tube, a minimum roof thickness of 100 m is required to preserve stability.