Crack Development Inside and Around Lunar Lava Tubes

Abstract

Evidence shows that lava tubes on the Moon, which constitute intriguing targets for exploration and long-term habitation, could be much larger than terrestrial tubes. However, existing observation strategies cannot confidently constrain the exact dimensions of lunar tubes in anticipation of in situ exploration. We produced and analyzed numerical models of the elastic gravity-induced deformation field around lunar lava tubes to determine where failure may occur on their internal surfaces and how the lunar surface above them may deform. This analysis suggests ways to determine tube dimensions from lunar surface morphological observations. The models predict extensive failure on the tube floors and roofs, leaving relatively small sections of pristine floor near the tube walls even if the tube itself may not collapse. The most extensive type of internal failure, tensile floor failure, depends on the tube shape. Additionally, the lunar surface around lava tubes develops cracks and subtle topographic bulges running parallel to the tube axis at distances proportional to the tube width. If observed, these could be used to determine the tube's width remotely. We examined several lunar sinuous rilles using orbital data to search for the surface features we expect near tubes. Linear cracks consistent with the presence of lava tubes are present on the possible extensions of three rilles: Rimae Mairan, Sharp, and Marius. Other locations did not show similar features, possibly because of the resolution of available data, tube depths, or surface degradation. However, surface or low-altitude observations would be more sensitive to the expected structures.