The NASA Lunar Reconnaissance Orbiter captured what could be entrances to underground caves near the moon’s north pole that could lead astronauts to water deposits. NASA/Lunar Reconnaissance Orbiter/SETI Institute/Mars Institute/Pascal Lee

Scientists might have found a cave system at the moon’s north pole that could lead astronauts straight to the lunar water supply.

The SETI Institute said this week that NASA’s Lunar Reconnaissance Orbiter took photos of a large crater in the area that appear to show entrances to underground passages known as lava tubes. According to SETI, they could potentially serve as access points for future astronauts searching for buried water ice on the moon.

That crater is the Philolaus Crater, which is more than 40 miles across and is relatively close to the lunar north pole. Scientists suggest there are entrances to lava tubes, sometimes called skylights, based on the appearance of “pits” in the crater. They are “small rimless depressions … with completely shadowed interiors.”

“The highest resolution images available for Philolaus Crater do not allow the pits to be identified as lava tube skylights with 100 percent certainty, but we are looking at good candidates considering simultaneously their size, shape, lighting conditions and geologic setting,” SETI planetary scientist Pascal Lee said in the institute’s statement.

Lava tubes get their name from the volcanic process that cleared them out. Finding many of them, experts have pointed to the subsurface chambers as potential exploration targets because of their scientific value. For starters, they could provide shelter to the next round of astronauts visiting the moon, as a sort of natural lunar base. They could protect the explorers from cosmic radiation and small meteorites — a function that also means they would be preserving lunar samples, shielding volcanic sediment and other material dating to the early years of the moon from the harsh lunar environment.

“Original lava compositions, textures and even magmatic volatiles are expected to be preserved in pristine condition within these lava tubes,” the Japan Aerospace Exploration Agency said when it discovered other lava tubes a few months ago.

Those preserved samples could give scientists insights into the moon’s history and how it formed.

Although previous lunar observations have identified hundreds of possible entrances to lava tubes, these are the first to find them in a polar region, according to SETI.

“The lunar poles have grown in strategic importance for both science and exploration, as water ice is known to be buried in the lunar regolith in permanently shadowed areas at both poles,” SETI said.

Regolith refers to the dust that coats the moon’s rock.

“But with no known large cavity allowing easy access to the lunar polar underground,” SETI added, “and often no nearby access to solar power, extracting water ice scattered in lunar polar regolith presents a substantial challenge.”

According to Lee, exploring lunar lava tubes would also give astronauts experience for when they potentially do the same thing on Mars and look for more than just water — they’d be looking for evidence of extraterrestrial life.