Yesterday, 45 years ago, humankind walked on another celestial body’s surface for the first time ever, making one of the wildest dreams of humanity come true. Now it seems that another long-existing fantasy – inhabiting it – is on its way to becoming reality as well. Again, the Moon is the selected destination, and some of its recently discovered features will likely help.
In one of his short stories, The Black Pits of Luna (1948), Heinlein described a boy visiting the Moon with his little sibling who gets lost (and eventually rescued). The description of our satellite is quite sketchy and consistent to what was known at the time, which was not a lot. But its title seems to have got it right in an odd way. We know now that not only the Moon’s surface is characterised by craters; there are deep holes as well. And, according to some recent observations from NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft, these holes are actually (black) pits. Even more interestingly, scientists believe that some of them lead to caves future dwellers could use as a shelter.
The first three of these pits were identified from images taken by the Japanese Kaguya probe (the largest spacecraft aimed at Earth’s satellite since the Apollo missions) launched in 2007.
Their dimensions vary widely – from tiny holes of around 5 meters to huge pits of 900 meters, with depth down to 100 meters – and around 200 of them have already been analysed and catalogued. They can be found both in young Copernican craters less than 1 billion year old and in lunar maria. Furthermore, their origin, whilst still object of debate, seems distinct from the craters themselves. The Pits were not formed by asteroids or meteoric impacts, and knowing more about them will also shed light on how the lunar maria were formed.
More interestingly for practical reasons, many of these pits are leading to a huge system of caves that could accommodate human settlements, more or less temporary. One of the main dangers astronauts of the Apollo missions had to face on the lunar surface was represented by environmental conditions. Underground pits can offer shelter from all issues caused by the lack of atmosphere, that makes life possible on Earth. They could therefore represent the first step toward the institution of moon colonies.
“Pits would be useful in a support role for human activity on the lunar surface. (…) A habitat placed in a pit — ideally several dozen meters back under an overhang — would provide a very safe location for astronauts: no radiation, no micrometeorites, possibly very little dust, and no wild day-night temperature swings.” (Robert Wagner, Arizona State University, July, 17, 2014) . In order to assess their suitability for human settlements, a more in-depth exploration is however needed. NASA planned to drop probes into one or two of the pits and collect essential data such as thermal measurements and gravity measurements. “Even a few pictures from ground-level would answer a lot of the outstanding questions about the nature of the voids that the pits collapsed into. We’re currently in the very early design phases of a mission concept to do exactly this, exploring one of the largest mare pits.” Wagner said. Stay tuned.