For astronauts exploring the lunar surface, there are some habitable places where they can hide to rescue themselves from radiation, micrometeorites, dust and wild day-night temperature swings.
NASA's Lunar Reconnaissance Orbiter (LRO) spacecraft has identified over 200 holes - steep-walled pits - that in some cases might lead to caves that future astronauts could explore and use for shelter.
"Pits would be useful in a support role for human activity on the lunar surface," said Robert Wagner of Arizona State University who developed the computer algorithm to scan thousands of high-resolution images of the lunar surface.
Most pits were found either in large craters with impact melt ponds or in the lunar maria (seas) - dark areas on the moon that are extensive solidified lava flows hundreds of miles across.
The pits could form when the roof of a void or cave collapses, perhaps from the vibrations generated by a nearby meteorite impact, according to Wagner.
Exploring the pits could also reveal how oceans of lava formed the lunar maria.
To date, the team has found over 200 pits spread across the melt ponds of 29 craters, which are considered geologically young "Copernican" craters at less than a billion years old, eight pits in the lunar maria and two pits in highlands terrain.
There are almost certainly more pits out there, given that LRO has only imaged about 40 percent of the moon.
"For about 25 percent of the moon's surface area (near the poles), the sun never rises high enough for our algorithm to work," Wagner said.
These areas will require an improved search algorithm.
The next step would be to tie together more datasets to gain a better understanding of the environments in which these pits form, both at and below the surface, Wagner concluded in a paper available online in the journal Icarus.
