Scientists have confirmed the existence of a cave on the moon, not far from where Neil Armstrong and Buzz Aldrin landed 55 years ago, and suspect that there are hundreds more that could house future astronauts.

An Italian-led team reported on Monday of evidence for a sizable cave accessible from the deepest known pit on the moon. It's located at the Sea of Tranquility, just 400 kilometers from the Apollo 11's landing site.

The pit, like the more than 200 others discovered there, was created by the collapse of a lava tube.

Researchers analyzed radar measurements by NASA's Lunar Reconnaissance Orbiter, and compared the results with lava tubes on Earth. Their findings were published in the journal Nature Astronomy.

The radar data reveals only the initial part of the underground cavity, according to the scientists. They estimate it's at least 40 meters wide and tens of meters long, likely even more extensive.

"Lunar caves have remained a mystery for over 50 years. So it was exciting to be able to finally prove the existence" of one, Leonardo Carrer and Lorenzo Bruzzone of the University of Trento, wrote in an email.

Most of the pits appear to be located in the moon's ancient lava plains, according to the scientists. There may also be some at the moon's south pole, the planned location of NASA's astronaut landings later this decade. Permanently shadowed craters there are believed to hold frozen water that could provide drinking water and rocket fuel.

During NASA's Apollo program, 12 astronauts landed on the moon, beginning with Armstrong and Aldrin on July 20, 1969.

The findings suggest that there could be hundreds of pits on the moon and thousands of lava tubes. Such places could serve as a natural shelter for astronauts, protecting them from cosmic rays and solar radiation as well as from micrometeorite strikes. Building habitats from scratch would be more time-consuming and challenging, even when factoring in the potential need of reinforcing the cave walls to prevent a collapse, the team said.

Rocks and other material inside these caves – unaltered by the harsh surface conditions over the eons – also can help scientists better understand how the moon evolved, especially in terms of its volcanic activity.