A typical forecast on the moon is far from comfortable, temperatures range from boiling during the day to 280 below zero at night. However, according to a new study, unique features known as the lunar pits could offer an oasis of roller coaster temperatures.
To find out what it might look like inside these lunar pits, a team of UCLA planetary scientists used NASA thermal imaging Lunar reconnaissance orbiter and determined that the temperature, at least in one of these pits, is always a constant 63 degrees. The findings were recently published in the journal Geophysical Research Letters, and the UCLA Newsroom is calling it the year-round “sweater weather” discovery.
One of the study’s authors, Tyler Horvath, who holds a doctorate in planetary science. student at UCLA said the pit could be the opening of a lava tube or a cave and would be an ideal place for astronauts to live, providing 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 are well above the boiling point of water. And then you have 15 days of extreme cold, which are among the coldest temperatures in whole solar system,” Horvath said. “So to be able to be in a place where you don’t have to expend energy to keep yourself warm for those 15 days of nighttime is almost invaluable because during the night, if you try to use solar energy as your main form of getting energy, you can’t do this for 15 days.
The UCLA research team focused on the Sea of Tranquility Chasm or Mare Trenquillitatis area, which is about 220 miles from where Apollo 11 landed and also equal distance from Apollo 17 landing site.
A cozy pixel on the moon
NASA’s LRO spacecraft is in continuous orbit around the moon, taking measurements with its suite of instruments, including the Diviner Lunar Radiometer, which has been constantly mapping the moon’s thermal emissions since 2009.
UCLA planetary scientist David Paige is the principal investigator of the Diviner instrument and the lead author of the new lunar pit study.
Horvath was commissioned to create a 3D model of one of these interesting pits in the Mare Trenquillitatis area. During this process, the team noticed a single pixel in the infrared images that was hotter than most points on the moon at night when temperatures drop.
“We noticed that very quickly it was able to heat up and maintain a higher temperature than the surface usually does at night,” Horvath explained. “We’re like, ‘Oh, this might be more interesting than we thought.'”
After rechecking the Diviner data and taking into account the sunshine in the pit, the team determined the temperature of the pit floor during the day. Unfortunately, this does not confirm the opening of a cave, but it is still the working theory of these pits formed by ancient volcanic activity.
“It was always a cool outcome that if there was a cave there, it would endure temperatures of 63 degrees Fahrenheit all the time, 24 sept every day forever,” Horvath said.
How the Trenquillitatis pit and other caverns on the moon maintain their temperature comes down to a physical concept known as the blackbody cavity, which can self-regulate to maintain its temperature.
“It’s basically a surface that’s a perfect radiation emitter and radiation absorber,” says Horvath.
The temperature at the bottom of the pit also depends on its position relative to the Earth and the Moon relative to the Sun.
“If you’re closer to the sun, the temperature would be warmer,” Horvath said. “If you are further from the sun, it will be colder.”
How did lava tubes form on the Moon?
Even from Earth, it’s obvious that the moon has some 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 on Earth.
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 completely leave and leave a hollow tube, a tube of lava below the surface,” Horvath said. “These pits are kind of our way of seeing that they exist, that there’s a way to get into them, and that they could be anywhere.”
NASA describes the lunar pits as “skylights” 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 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 descending into one of these pits, it will be difficult for researchers to know if these vast caves exist. Eventually, it might be possible because, over the next four years, NASA plans to return humans to the Moon and establish a permanent base.