Researchers have found evidence of a sizable underground cave on the Moon that is accessible from the surface, making the site a prime location to build a future lunar base.
The cave appears to be accessible from a hole in the Mare Tranquillitatis (Sea of Tranquility), the ancient lava field where Apollo 11 astronauts Neil Armstrong and Buzz Aldrin first set foot on the Moon more than half a century ago.
Analysis of radar data collected by NASA’s Lunar Reconnaissance Orbiter (LRO) revealed that Mare Tranquillitatis Crater, the deepest known crater on the Moon, leads to a cavern 45 meters wide and up to 80 meters deep. long, an area equal to 14 tennis courts. The cave lies about 150 meters below the surface.
Lorenzo Bruzzone, of the University of Trento in Italy, said the cave was “probably an empty lava tube”, adding that such features could serve as human habitats for future explorers as they were “a natural shelter against the harsh lunar environment “.
Lunar orbiters first discovered craters on the Moon more than a decade ago. Many are thought to be “skylights” associated with underground caverns such as lava tubes, giant underground tunnels that form through volcanic processes.
Such caves could form the basis for a lunar base or an emergency lunar shelter because the temperature is relatively stable inside and astronauts would naturally be protected from harmful cosmic rays, solar radiation and micrometeorites.
Previous images taken by LRO showed that the bottom of the Mare Tranquillitatis crater was strewn with boulders up to 10 meters wide. But it was unclear whether the pit was sealed or served as an entry point to an underground cavern, such as a lava tube whose roof had collapsed.
Writing in Nature Astronomy, the scientists describe how they used LRO data and computer simulations to show that the 100-meter-wide pit, which is bordered by vertical or hanging walls, leads to a sloping floor and a cavern that stretches for tens of meters to the west. .
Researchers are keen to study the rocks inside such caves as they likely hold clues to the Moon’s formation and volcanic history. The caves may also contain water ice, a resource Bruzzone said was essential for long-duration lunar missions and colonization.
At least 200 craters have been seen on the Moon, and many found in lava fields may be entrances to underground lava tubes. “The main advantage of caves is that they make available the main structural parts of a possible human base without requiring complex construction activities,” said Leonardo Carrer, the first author of the study.
In preparation for the return of humans to the Moon, space agencies are already asking how to assess the structural stability of caves and reinforce their walls and ceilings. Habitats may also need monitoring systems to warn of movement or seismic activity, and have special areas for astronauts to retreat to if parts of their cave collapse.
“Lunar cave systems have been proposed as excellent places to locate future crew bases, as the thick rock cave ceiling is ideal for protecting people and infrastructure from the wild day-night temperature changes of the lunar surface and for block the high energy radiation that washes away. the lunar surface,” said Katherine Joy, professor of earth sciences at the University of Manchester. “However, we currently know very little about the underground structures beneath these sinkhole entrances.”
Robert Wagner, a researcher at Arizona State University, said one of the biggest challenges would be access. “To get into that hole you have to go down 125 meters before you get to the floor, and the edge is a steep slope of loose debris where any movement will send small avalanches to whoever is below,” he said. “Of course it’s possible to get in and out, but it’s going to take a significant amount of infrastructure.”