Effects of layered roof for stability and exploration of lunar lava tubes

• Lunar lava tubes with stratified roofs and weaker interlayers are less stable than those with homogeneous rock. • Local collapses in stratified roofs occur as rock slices, exposing lower paleoregolith layers. • Large amounts of rock debris and boulders are predicted in lava tubes, requiring special technology for access. • The cohesion ratio between layers in a stratified roof influences collapse types. Lunar lava tubes, of which possible existence as tunnel-like structures has been anticipated, may serve as shelters for future exploratory missions and places for groundbreaking scientific research. One major issue in planning exploratory missions is the lack of realistic safety assessment. We introduce evident layering of lunar collapse pits walls to model their stability and applied a recently proposed probabilistic approach to account for their unknown shapes. We demonstrate a dominance of local collapses that do not reach the lunar surface for layered roofs. Our results suggest that pristine peleoregolith layers may be exposed inside lunar lava tubes due to the common occurrence of such local collapses, which can yield unique geological/astrophysical recordings from previous epochs. We demonstrate that multiple local collapses may also explain the observable geometries of lunar collapse pits, leading to improvement of the overall stability of the post-collapse lava tube configuration.