Lunar Astronauts Could Set Up Camp in Underground Cave Systems on the Moon

Science fiction is riddled with stories of humanity making a permanent expansion into space. In each of those imagined futures, we figure out ways to survive and thrive in space, long-term. Off Earth, our bodies would be exposed to microgravity, increased radiation, and alien environments. If we want to survive for even short periods, we have to take all of the comforts of home with us.

SYFY’s The Ark solved that problem (or endeavored to) by putting its passengers in stasis. If they had remained that way for the duration of the trip, things would have worked out fine. Instead, their ship took some damage, much of the crew died, and now they’re stranded in deep space. The 1975 sci-fi series Space: 1999 (now streaming on Peacock) stays closer to home, at least at the beginning. Scientists set up a research station called Moonbase Alpha inside a crater on the Moon.

The fictional base extends approximately a kilometer beneath the lunar surface, where explorers and researchers live and work full time. The residents of Moonbase Alpha (along with the rest of the Moon) ended up cruising off into deep space after the nuclear waste on the Moon’s far side detonated like a giant rocket engine. That is, of course, ridiculous, but the semi-subterranean Moonbase design might be pretty close to what we actually end up with.

Future Moon Bases Could Be Built Inside Underground Lava Tube Caves

A lunar collapse pit in Mare Tranquillitatis is about 100 meters across and leads to a lava tube below. Temperatures inside the tube are quite clement. Photo: NASA/GSFC/Arizona State University

There is a giant hole in the surface of the Moon, about 230 miles northeast of the Apollo 11 landing site. It’s called Mare Tranquillitatis and it was first spotted in 2009. Since then, scientists have studied the pit and others like it to see if they might make suitable lunar neighborhoods. That’s a particular challenge, considering the Lunar Reconnaissance Orbiter (LRO) has to study them from dozens of miles above the Moon’s surface.

As the LRO makes its circuitous paths around the Moon, it has the opportunity to take images of the pit from various angles. When flying directly overhead, the orbiter can see straight down to the bottom, and when it’s on approach or on its way out, it can glimpse beyond the edges of the pit. In that way, astronomers have confirmed the presence of a cave system of lava tubes a few hundred feet beneath the surface.

Scientists believe the caves were created by lava tubes left over from when the Moon was more geologically active. As ancient lunar magma pushed its way toward the surface, carving channels through the rock which drained and were left behind. In some places, those subterranean tubes have collapsed, revealing entry pits at the surface. Hundreds of these pits have been discovered in recent years and researchers believe that a dozen or more of them lead to underground cave systems.

While there is still a lot to learn about these caves, they could provide precisely what we’re looking for in a lunar home. A couple hundred feet of rock would do quite a bit to shield lunar astronauts from the harsh conditions of space. Surface temperatures of the Moon range from 260 Fahrenheit in the sunlight to negative 280 Fahrenheit during lunar night. Worse, the Moon’s slow rotation means that each period of day and light lasts about two weeks.

Any base on the surface would have to deal with wide swings in temperature every fortnight, but a subterranean Moonbase could avoid some of that. Analysis of Mare Tranquillitatis revealed permanently shaded regions at the bottom which stay at a comfortable 63 degrees all the time. Scientists expect that any connected cave systems would have similar temperatures. It’s not exactly a tropical vacation destination, but it’s close enough, and consistent enough, to work with.

The only real downside is that, despite having finally made it to the stars, we won’t be able to see them beneath a few hundred feet of rock.

Watch new Season 2 episodes of The Ark Wednesdays on SYFY, or catch up on the previous season on Peacock, alongside Space: 1999 and a wide collection of more sci-fi favorites!