Data from GRAIL spacecraft suggest moon may have large lava tubes

A team of researchers with Purdue University has found evidence from lunar-mapping spacecraft that the moon may have large lava tubes that could conceivably be used to house astronauts and supplies. <...>

Prior research here on Earth has shown that lava flowing across a surface can form a shell of sorts as it cools, and when the shell collapses, a hollowed-out underground space remains—geologists call them lava tubes. Examples have been found in Hawaii and Iceland. Now, the researchers at Purdue believe they have found evidence that such structures might exist just below the surface of the moon in some places as well.
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The model indicated that lava tubes were likely present and that they could be as wide as three miles across and still remain stable. Such a wide, long tube, the researchers note, might be an ideal form of shelter for future astronauts—they could live in the tubes along with all their gear free from the fear of being struck by space debris and the constant barrage of solar radiation. It would likely be easier to manage temperature control as well, making life less dangerous for future moon residents.

Если вкратце, на Луне найдены признаки существования гигантских лавовых труб — туннелей естественного происхождения, ширина которых может превышать 1 км. Возможно, эти нерукотворные полости пригодятся будущим лунным колонистам для защиты от метеоритов и солнечного излучения.

P.S. Лавовая трубка — Википедия