The temperature on the moon can range from boiling to freezing depending on whether it’s night or day, but scientists believe there may be sheltered pits and caves where the temperature is quite reasonable – no matter what time it is.
In such places, the temperature hovers around 17 degrees Celsius (63 degrees Fahrenheit), according to new calculations. They could be ideal places to establish base camps for exploring the rest of the lunar surface.
They can also offer some protection against small meteorites and even from harmful solar radiation coming from the Sun. With a convenient base, future lunar settlers could focus on other endeavors, such as growing food or conducting research.
“Humans evolved living in caves, and we may return to caves when we live on the moon,” says planetary scientist David Page of the University of California, Los Angeles (UCLA).
We’ve known about craters on the moon for several years. The researchers used images taken by NASA’s Lunar Reconnaissance Orbiter (LRO) – specifically its Diviner Lunar Radiometer Experiment thermal camera – to try to estimate the temperature in a pit in the Moon’s Mare Tranquillitatis region.
Using computer models to analyze the thermal properties of the rock over time, the researchers estimated that the sunlit part of the pit could trap heat to bake hotter than the surface, reaching up to 300 degrees Celsius.
Yet, in the nearby shadows, trapped heat can raise otherwise freezing cold temperatures to something a little more moderate and keep them there even after the sun goes down.
The next question is whether these overhangs have enough space for a community of researchers to congregate. Pictures from space suggest that some of them do – and indeed this is the case on Earth, where the tunnels are left by molten lava flowing beneath the surface. Some pits may be collapsed lava tubes.
Part of the research involved aligning and matching multiple photos, removing inconsistencies until the team could estimate the temperatures of individual pixels in the images captured by LRO.
“Because no one else was looking at things this small with Diviner, we found that there was a little bit of double vision, which made all our maps a little blurry,” says planetary scientist Tyler Horvath, also of UCLA.
Each day and each night on the Moon lasts about 15 days on Earth, with temperatures ranging from about 127 degrees Celsius (261 degrees Fahrenheit) during the day to about minus 173 degrees Celsius (minus 279 degrees Fahrenheit) at night.
Both people and equipment would need protection from these extremes during long-term lunar exploration projects, which would be quite an engineering challenge; finding an inhabited cave or two would be a very convenient shortcut.
NASA plans to further explore the region during the proposed Moon Diver mission, which would see a rover descend into the Mare Tranquillitatis crater and check for any cave networks it may be connected to.
“Moon craters are a fascinating feature of the lunar surface,” says planetary geologist Noah Petro of NASA’s Goddard Space Flight Center in Maryland. “Knowing that they create a stable thermal environment helps us paint a picture of these unique lunar features and the prospect of one day exploring them.”
The research is published in Geophysical Research Letters.
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