New observations of the Moon reveal that lunar water may be more accessible than originally thought. The new data is particularly exciting for NASA, which hopes to leverage the Moon’s resources — notably water ice embedded in the soil — to help future astronauts live and work on the lunar surface.
In one study, researchers detected water directly on the lunar surface, finding the molecule on areas of the Moon lit by the Sun. A second study speculates that water ice might be trapped in tiny pockets or small craters littered all over the Moon’s surface, making water potentially more abundant and more accessible than we could have imagined. The two studies were published today in the journal Nature.
This isn’t the first time water has been detected on the Moon. But the only water we’ve been able to find and verify up until now is really difficult to reach. It seems to be primarily located in large craters at the lunar south pole that are in perpetual shadow. The frigid craters are dangerously cold — possibly reaching -400 degrees Fahrenheit — making them practically impossible to access with modern technology. “They happen to be the coldest known places in the Solar System, believe it or not,” Paul Hayne, a planetary scientist at the University of Colorado and a lead author on one of the Nature studies, tells the The Verge.
The research published today raises the possibility that astronauts can find water in other areas of the Moon that are far less deadly. “If we find that it’s abundant enough in certain locations, it would be easier to access versus going into these very cold, very dark places,” Casey Honniball, a postdoctoral fellow at NASA’s Goddard Space Flight Center and lead author on one of the studies, tells The Verge.
Extracting water ice from the Moon is an attractive idea for anyone hoping to put a base or settlement on the lunar surface. If it’s purified, lunar water could be used as drinking water or as hydration for plants. Water can also be broken apart into its basic components — hydrogen and oxygen — and turned into rocket fuel. It takes a lot of energy, time, and money to send supplies to the Moon, so if astronauts can use what’s already up there, that would cut down on shipments from Earth and help the astronauts sustain themselves.
For the last two years, NASA has been squarely focused on sending people to the Moon for its Artemis program, with the agency touting “sustainability” as the ultimate goal. In support of that mission, NASA has also been very vocal about mining any water ice that is present on the Moon. NASA administrator Jim Bridenstine often makes the claim that we know there are “hundreds of billions of tons of water ice on the surface of the Moon.”
The truth is, we don’t really know that. All we have are estimates based on a few detections over the last couple of decades. The first big confirmation of water came in 2008, when data from India’s Chandrayaan-1 spacecraft showed signs of water-like molecules at the lunar south pole. NASA then launched a spacecraft called LCROSS which rammed into the Moon in 2009, kicking up material and confirming that water in some form was present. And in 2018, researchers using data from that same spacecraft found direct evidence of water ice at the poles. But ultimately, we just have approximate ideas about how much water might be up there — nothing concrete. Also we don’t know what the ice really looks like. Is it evenly dispersed throughout the lunar soil or is it clumped together in large chunks?
These new studies don’t give us a concrete answer, either, but they hint that water does exist in areas that won’t kill people. To find this water, Honniball and her team flew NASA’s SOFIA observatory, a Boeing 747 equipped with telescopes and instruments to study objects throughout the Universe. SOFIA’s data helped Honniball find actual molecular water on sunny surfaces of the Moon. Its existence came as a surprise. “We didn’t know that water could survive on the surface of the Moon when it is illuminated” she says. Honniball speculates that the water molecules are embedded within dark lunar particles and grains often found on the Moon’s surface.
The second study didn’t detect water directly but finds that there are essentially mini-craters or tiny shadowed regions dotting the the surface of the Moon. After analyzing these areas closely using images taken by NASA’s Lunar Reconnaissance Orbiter, the researchers believe these small regions are cold enough to store frozen ice. Unlike the giant craters at the south pole, these ones are small and easy for, say, an astronaut to reach. “There are billions and billions of them, which means that you could land in an area that is lit by the Sun, and then bend over or get down on your hands and knees and extract samples from from these micro-cold traps,” says Hayne. He and his colleagues estimate that 40,000 square kilometers (around 15,400 square miles) of the Moon are capable of trapping water this way.
At first glance, this spells good news for NASA. But there are still a lot of unknowns associated with this research. While the first study detected water, the researchers didn’t find a lot — about the equivalent of a 12 ounce bottle of water trapped in a cubic meter of soil that’s spread across the Moon. Plus, if the water is embedded in the lunar dirt as expected, it’s going to take a lot of work to extract. “The method to extract that water would be to melt the glass, so that the water can be released,” Honniball says. “This is a consuming process, compared to some other methods.”
When it comes to the tiny cold traps, we don’t actually know if water ice is lurking in them, either. Their conditions may be just right to hold water ice, but the researchers didn’t directly detect water in the traps.
NASA and private companies are working to get more direct information from the Moon’s surface. In late 2023, NASA plans to send a rover to the Moon called Viper, which will map where the water ice is on the surface and collect samples. Even before that happens, a private company called Intuitive Machines plans to send a robotic lander to the lunar surface in 2022, equipped with the same drill that Viper will use. That mission, done in partnership with NASA, should demonstrate if the drill is able to work and scoop up some of this water ice.
Data from those rovers, combined with future remote observations, will eventually determine whether future lunar astronauts will be able to use any of this water. Until then, NASA and other agencies with lunar ambitions will stay thirsty for more information about the perpetually elusive water on the Moon.