In such places, the temperature hovers around 17 degrees Celsius (63 degrees Fahrenheit), according to new calculations. They could be ideal locations for establishing base camps for exploring the rest of the lunar surface. They may also offer some protection from small meteors and even from harmful solar radiation from the Sun. With a comfortable base, future lunar colonists could focus on other endeavors – like growing food or conducting research. “Humans evolved by 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 have known about craters on the Moon for several years. The researchers used images taken by NASA’s Lunar Reconnaissance Orbiter (LRO) – specifically the Diviner Lunar Radiometer Experiment thermal camera – to try to measure the temperature inside a pit in the Moon’s Mare Tranquillitatis region. Using computer models to analyze the thermal properties of the rock over time, the researchers calculated that the sunlit part of the pit could retain heat to bake hotter than the surface, reaching up to 300 degrees Celsius. However, in the nearby shadows, the trapped warmth could raise the otherwise frigid temperatures to something a little more temperate and keep it there even after the Sun goes down. The next question is whether these ledges have enough room to squeeze in a community of explorers. Images from space suggest that some of them do – and indeed, this is what happens on Earth, where tunnels are left behind by molten lava flowing beneath the surface. It is possible that some pits are lava tubes that have collapsed. Part of the research involved aligning and collecting multiple photos, removing inconsistencies until the team could calculate the temperatures of individual pixels in the images taken by LRO. “Because no one else had looked at things this small with the Diviner, we found that it had a little bit of double vision, so all of our maps were 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 research projects, which would be quite an engineering challenge. Finding a habitable cave or two would be a very convenient shortcut. NASA plans to explore the area further during the proposed Moon Diver mission, which would see a rover drop into the Mare Tranquillitatis crater and check for any cave networks it might connect to. “Lunar craters are a fascinating feature on 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 these unique lunar features and the prospect of exploring them one day.” The research was published in Geophysical Research Letters.
