Future Moon Bases Might Be Built in Underground Lava Tubes

Caverns carved out by ancient lava could shelter astronauts from the hazards of moon life

marius hills pit
Features like the Marius Hills pit could be skylights in lava tubes that could one day house underground moon bases. NASA/GSFC/Arizona State University

Science fiction writers have spent decades imagining what future moon colonies might look like. Early plans for moon bases have been proposed by space agencies including NASA, the European Space Agency, and the Japanese Aerospace Exploration Agency, but designing a permanent lunar base is not an easy proposition. There is one concept, however, that scientists believe may help develop future moon bases: build them in underground lava tubes.

For years, scientists have proposed that the moon is riddled with lava tubes left over from its early, geologically active days. Lunar researchers believed that some previously observed features could be lava tube "skylights," or openings into enormous underground caverns. But until now, the best evidence of tubes came from studying the moon’s surface.

Last week, scientists speaking at the Lunar Planetary Science Conference announced that new analysis of the moon’s gravity field could provide new evidence for these tunnels’ existence, Nadia Drake reports for National Geographic.

“[This is] the strongest evidence yet that shows signals consistent with that of buried, empty lava tubes on the moon,” Purdue University researcher Rohan Sood, who presented the findings at the conference, tells Drake.

Sood and his colleagues based their research on gravitational data gathered by NASA’s twin GRAIL spacecraft in 2012. Because the strength of the moon’s gravitational field varies depending on mass below the surface, areas where there is more mass underground will give off different readings than a region that is hollow, Drake reports.

“If you fly over a lava tube, there’s going to be a dip in gravity,” Sood tells Drake.

After going through the GRAIL data, Sood and his team identified 10 different regions that could hold giant underground caverns and lava tubes that were also positioned near features believed to be skylights or other openings on the surface. The potential laval tubes are all located in an area on the near side of the moon known to have been volcanically active in the past, and are big enough to contain entire cities, Drake reports.

The lava tubes could provide important information about the moon’s volcanic history. And if they do exist they could also be ideal spots for long-term settlements.

Colonists living on the moon’s surface would have a variety of serious environmental conditions to contend with, including cosmic radiation, severe temperature swings and micrometeoroid collisions, Erik Shilling reports for Atlas Obscura. While some moon village plans propose dealing with these issues by building shelters out of cement, repurposed modules from the International Space Station, or deep inside lunar craters, constructing a settlement within an enormous lava tube could provide a natural, cost-effective shield for future colonists.

While Sood’s findings are a good sign, more research is necessary to confirm whether there are ancient lava tubes buried beneath the moon’s surface. Sood’s team has proposed sending a robotic spacecraft to scan the moon specifically for signs of lava tubes, but for now there are no official plans for a specific mission to follow up on the findings.

If the lava tubes are there, though, future astronauts might one day set up camp inside them.