Scientists have discovered a massive underground cave on the Moon which would act as an ideal base for future lunar explorers. Scientists analyzed radar data received from NASA’s Lunar Reconnaissance Orbiter, or LRO, to come up with detailed features of the cave accessible from the deepest known pit on the Moon, lying in Mare Tranquillitatis, or Sea of Tranquility.
Although Mare Tranquillitatis is a famous landing place of Apollo 11 astronauts Neil Armstrong and Buzz Aldrin over half a century ago, the newly discovered cave can be reached from an open pit in this ancient lava plain. The shape is believed to be about 45 meters wide and up to 80 meters in length, equivalent to 14 tennis courts. It lies about 150 meters beneath the lunar surface.
According to Lorenzo Bruzzone from the University of Trento in Italy, the cavity was probably just an empty lava tube that would provide a natural environment for the astronauts. “Such features could provide a natural shelter against the harsh lunar environment,” he said. Since these caves provide very stable temperatures and protection against cosmic rays, solar radiation, and micrometeorites, they are prime candidates for future moonbases or emergency shelters.
The concept of lunar pits and caves is not new. Many of these pits were first detected by lunar orbiters more than a decade ago, and most are believed to be skylights that open into subterranean lava tubes created by volcanic activity. Earlier LRO images of the Mare Tranquillitatis pit showed it was littered with boulders, but it wasn’t clear if the pit opened into an underground cave. The latest research, published in Nature Astronomy, has confirmed that the pit indeed leads to a sloping floor and a cave extending tens of meters westward.
These caves can provide rocks that may include critical clues related to the formation and volcanic history of the Moon. The caves might also have water ice, a critical resource for either long-term lunar missions or lunar colonization. Leonardo Carrer, an author of this study, said “They make available the main structural parts of a possible human base without requiring complex construction activities.”
But both caves are highly inaccessible. Robert Wagner of Arizona State University said that getting into the pit meant descending a steep slope of loose material, which could easily initiate avalanches. “It’s certainly possible to get in and out, but it will take a significant amount of infrastructure,” he said.
Such a cave discovery opens up new vistas for lunar exploration and habitability. Katherine Joy, a professor of Earth sciences from the University of Manchester, said these caves could offer natural protection from extreme lunar conditions for future crewed bases. But still, so much is yet unknown by scientists about the underground structures beneath these pit entrances.
The structural stability of these caves will have to be assessed, with reinforcements made to their walls and ceilings in preparation for the humans’ arrival on the Moon. Also very important is a monitoring system to track any sort of movement or seismic activity and specific retreat areas for the astronauts in case of cave collapses.
This isn’t the only development that’s promising for lunar habitation; it also provides a window into the Moon’s geological history. Rocks inside these caves, relatively unaltered by harsh surface conditions, could provide a long record of geologic processes going back billions of years. The study would also lead to exploring caves on Mars and open a potential window to finding evidence of life on the Red Planet.
According to Francesco Sauro, Coordinator of the Topical Team Planetary Caves of the European Space Agency, “There are huge opportunities for discovery.” This cave on the moon could be the stepping stone towards understanding not just the Moon itself but the broader history of our entire solar system.