This story originally appeared on WIRED Italy and was translated from Italian.
Their existence has been questioned for decades, but now we can finally say for sure: there are caves beneath the moon’s surface. This week, an international research team led by the University of Trento in Italy published test in Nature Astronomy showing evidence of accessible areas beneath the lunar surface. The discovery could be crucial for building future colonies on the Moon.
For more than half a century, astronomers have theorized that a network of caves and tunnels exists beneath the moon’s surface. In 2009, a team of experts identified a deep hole on the moon’s surface, supporting the idea that underground caves may have formed on the moon as lava cooled beneath the surface. This week’s discovery provides evidence of longer underground channels. “These structures have been hypothesized for more than 50 years, but this is the first time we have proven their existence,” says Lorenzo Bruzzone of the University of Trento, research coordinator.
To make the discovery, scientists analyzed data collected in 2010 by a radio instrument on NASA’s Lunar Reconnaissance Orbiter, a spacecraft that has been orbiting the moon since 2009, mapping its surface and looking for potential landing sites for future missions. From the images, scientists were able to reveal a hidden, emptied lava tube in the Sea of Tranquility region that could one day be accessible to astronauts.
“We analyzed these images using complex signal processing technologies recently developed in our laboratory and found that part of the radar reflections from the Sea of Tranquility area can be attributed to an underground conduit,” Bruzzone says. “This discovery provides the first direct evidence of an accessible rock tunnel beneath the lunar surface.” Data analysis also allowed scientists to construct a model of the initial part of the tunnel. “It is very likely that it is an emptied lava tube,” says Leonardo Carrer, a researcher at the University of Trento and the first author of the paper.
The findings could have essential implications for future lunar missions. Meteorites and radiation make the lunar environment hostile to humans—cosmic and solar radiation are up to 150 times more intense than those experienced on Earth, and the threat of meteorites is constant. That’s why it’s imperative to find sheltered areas for landing sites or building long-term lunar infrastructure. Astronauts could one day find shelter in these caves.