Dark Pits on the Moon May Be the Comfiest Hangouts for Humans

Future moon astronauts might want to pack a light sweater.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
2 min read
Gray moon surface broken by a deep pit, partly in shadow with boulders on the bottom.

This Lunar Reconnaissance Orbiter view of the Mare Tranquillitatis pit shows a dark shadow, and boulders lit up on the floor. 

NASA/GSFC/Arizona State University

NASA's Lunar Reconnaissance Orbiter spacecraft, or LRO, may have helped find the key to comfort for astronauts spending an extended time on the moon. They could become cave people -- or pit people.

The lunar surface isn't friendly. It can get blazing hot during the day and wicked cold at night. If humans are going to have a sustained presence on the moon, that means figuring out how to keep them safe and comfortable. How does 63 degrees Fahrenheit (17 Celsius) sound? Pretty good compared with lunar surface extremes of up to 260 degrees Fahrenheit (127 Celsius) and down to minus 280 Fahrenheit (minus 173 Celsius).

Three shadowy images of the same pit seen in separate images of the moon's surface.
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Three shadowy images of the same pit seen in separate images of the moon's surface.

These LRO snapshots show a pit in Marius Hills on the moon seen at three different times. The lighting shows how part of it stays in shadow.

NASA/GSFC/Arizona State University

Planetary science doctoral student Tyler Horvath of the University of California, Los Angeles is the lead author of a paper on moon pits published in the journal Geophysical Research Letters this month. The study used data from LRO's Diviner thermal camera along with computer modeling to work out that permanently shadowed areas within some of the moon's pits stay at a pleasant temperature. 

The study focused in on a 330-foot (100-meter) deep pit in an area called Mare Tranquillitatis. The researchers found that "the pit's thermal environment is more hospitable compared to anywhere else on the moon." UCLA described it as "always sweater weather." That may be thanks to an overhang that casts a shadow down below.

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Scientists have known about the existence of lunar pits since 2009. Some of those collapsed areas might lead to lava tubes, empty tunnels left behind by long-ago volcanic action. Besides nice temperatures, lunar caves could also help protect astronauts and equipment from radiation and small meteorites. 

Researchers had already been considering lava caves on the moon and Mars as potential sites for human habitats, so this new information on the temperature is a welcome addition to that work.

Robotic explorers would most likely do the legwork into pits and caves before astronauts try to peek inside. NASA has tested out a spelunking robot named Moon Diver inside Hawaiian lava tubes. The space agency is still working on getting humans back to the moon for a brief visit through the Artemis program, so any realistic talk of building lunar stations inside caves is a long way off. But those caves are looking pretty tempting now.