Are there huge lava caves on the moon?

Volcanism and low gravity could have left big caves

Such depressions of old lava flows - here in the moon-cat Aridaeus - could indicate the existence of lava-caves. © NASA
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Hollowed out by lava: On the moon there could theoretically be huge lava caves - just like in Hawaii much larger. Because the once intense volcanism on our satellite and the low gravity would allow even kilometer-sized cavities, as US researchers have now determined. If they really exist, they would be ideal places for future lunar stations.

The moon has a volcanically very active past: the vast dark mare on the moon side facing us consist entirely of cooled basalt lava and on the opposite side there are old fire mountains - one of them even shows a fairly large eruption.

Suspicious lunar grooves

However, the question of whether there are lava caves on the moon - caverns that are formed when glowing lava flows initially only cool on the outside and then form a kind of tube - has been left open. "There was some discussion on whether such lava tubes could exist on the moon, " explains Jay Melosh of Purdue University. "There's some evidence for that, including winding hollows on the surface."

These meandering valleys are up to ten kilometers wide and several hundred kilometers long. They resemble a few riverbeds, but are more likely attributed to lava flows - also because they usually begin at one of the old lunar volcanoes. Theoretically, it is possible that the lava that once flowed in these beds also formed lava tubes - caves that are now hidden under the regolith.

The lava caves would still be stable on the moon even at several kilometers in diameter. © Purdue University / David Blair

Big enough for a whole city

"If there's a lava tube on the moon, they might even be really big, " says Melosh. Because the lower gravity still allows vaulting, which would collapse on earth, as the researchers now found in a study. With the help of model calculations, they checked whether an empty lava tube with a diameter of more than one kilometer could remain stable on the moon. display

The result: "Lava tunnels with a shape similar to those on Earth could even be several miles wide on the Moon, " says first author David Blair of Purdue University. In addition to the lower gravity, the weather and erosion are lower than on Earth. "In theory, therefore, huge, structurally stable lava tubes could exist on the moon large enough to accommodate a whole city, " Blair said.

Whether such lava tubes actually exist, has yet to be seen. If this is the case, then they would be perfectly suited, for example, to protect a moon station from the cosmic rays and the extreme temperature fluctuations on our satellite. (Lunar and Planetary Science Conference, 2015)

(Purdue University, 07.04.2015 - NPO)