A typical lunar forecast is anything but welcoming, with temperatures ranging from boiling during the day to minus 280 at night. However, according to a new study, unique features known as craters on the moon could offer an oasis from the roller-coaster temperatures.
To find out what it might be like inside these lunar pits, a team of planetary scientists from UCLA used thermal images from NASA’s Lunar Reconnaissance Orbiter and determined that the temperature, in at least one of these pits, is always 63 degrees. The findings were recently published in the journal Geophysical Research Letters, and the UCLA editorial team is calling it the discovery of year-round “sweater weather.”
One of the authors of the study, Tyler Horvath, Ph.D. in planetary sciences. student at UCLA, said the pit could be the opening of a lava tube or cave and would be an ideal place for astronauts to live, offering perfect temperatures as well as protection from meteorites and radiation.
“Imagine a full day on the moon … you have 15 days of extreme heat that reaches well beyond the boiling point of water. And then you have 15 days of extreme cold, which are some of the coldest temperatures in the entire solar system,” Horvath said. “So to be able to be in a place where you don’t have to spend energy to stay warm for those 15 days at night is almost priceless because at night, if you’re trying to use solar energy as your primary way of getting energy, you can’t do it for 15 days.”
The UCLA research team focused on the Sea of ​​Tranquility trough, or Mare Trenquillitatis region, which is about 220 miles from where Apollo 11 landed and also in the same distance from the Apollo 17 landing site.
A cozy pixel on the moon
UCLA researchers spotted a single pixel in the infrared images that suggests there are warmer spots on the Moon. NASA/GSFC/Arizona State University
NASA’s LRO spacecraft is continuously orbiting the Moon, taking measurements with its suite of instruments, including the Lunar Diviner Radiometer, which has been mapping the Moon’s thermal emissions continuously since 2009.
UCLA planetary scientist David Paige is principal investigator of the Diviner instrument and lead author of the new moonwell study.
Horvath was commissioned to create a 3D model of one of these interesting pits in the Mare Trenquillitatis region. During this process, the team noticed a single pixel in the infrared images that was warmer than most spots on the Moon at night when temperatures plummet.
“We noticed that it was able to heat up very quickly and maintain a warmer temperature than the surface usually does at night,” Horvath explained. “We’re like, ‘Oh, this might be more interesting than we thought.'”
Japan’s SELENE/Kaguya Terrain Camera and Multiband Imager captured the moon’s ancient volcanic region called the Marius Hills.NASA/GSFC/Arizona State University
After rechecking the Diviner data and considering how much sunlight the pit receives, the team determined the temperature of the pit’s floor during the day. Unfortunately, this does not confirm the opening of a cave, but this is still the working theory about these pits formed by ancient volcanic activity.
“It was still a fantastic result that if there was a cave there, it would withstand temperatures of 63 degrees Fahrenheit all the time, 24 degrees Celsius every day forever, basically,” Horvath said.
The way Trenquillitatis pit and other lunar caverns maintain their temperature comes down to a physical concept known as a blackbody cavity, which can self-regulate to maintain its temperature.
“It’s essentially a surface that is a perfect emitter of radiation and a perfect absorber of radiation,” explains Horvath.
The temperature at the bottom of the pit also depends on its position relative to the Earth and the moon.
“If you’re closer to the sun, the temperature would be hotter,” Horvath said. “If you are farther from the sun, it would be colder.”
How did lava tubes form on the Moon?
Even from Earth, it’s obvious that the moon has interesting features, including craters of all shapes and sizes. In 2009, the Japanese Kaguya spacecraft orbiting the Moon discovered a new type of lunar feature in the form of deep chasms that researchers believe may contain caves created by collapsed lava tubes, similar to those found in the earth.
UCLA researchers believe the Moon has lava caves similar to Devil’s Throat in Hawaii Volcanoes National Park. Sergi Reboredo/VW PICS/Universal Images Group via Getty Images
Horvath explains that billions of years ago, very intense volcanic activity and lava flows created the dark spots we see today when we look at the moon. The lava on the surface would cool first because it was exposed to the cold temperatures of space where the caverns beneath the lava were still flowing.
“In some places, this lava will come out completely and leave a hollow tube, a lava tube below the surface,” Horvath said. “These wells are kind of our ways of seeing that they exist, that there’s a way to get into them, and that they could be everywhere.”
NASA describes the moon pits as “clarinyards” where the roof of the lava tube collapsed.
On Earth, the UCLA research team behind the study even visited a lava tube in Hawai’i Volcanoes National Park known as Devil’s Throat, which is similar size to the Mare Trenquillitatis pit. The park is home to other lava tubes like the one pictured above that visitors can walk through.
Without physically going to the moon and climbing rocks into one of these pits, it will be difficult for researchers to know if these large caves exist. Finally, this could be possible because, within the next four years, NASA plans to return humans to the Moon and establish a permanent base.