According to recent research led by the University of Colorado Boulder, hidden pockets of water on the moon’s surface may be far more widespread than scientists previously thought. These tiny patches of ice may exist in permanent shadows no bigger than a cent in some situations.
“If you can imagine standing on the surface of the moon near one of its poles, you would see shadows all over the place,” said Paul Hayne, assistant professor in the Laboratory of Atmospheric and Space Physics at CU Boulder. “Many of those tiny shadows could be full of ice.”
Hayne and his colleagues investigated “cold traps,” shady parts of the moon’s surface that exist in an everlasting state of darkness, in a study published today in the journal Nature Astronomy.
Many people have gone billions of years without seeing a single ray of sunlight. And there’s a good chance that these nooks and crannies are far more prevalent than past data suggests.
The researchers believe that the moon could have around 15,000 square miles of permanent shadows in various forms and sizes reservoirs that, in principle, could also be capable of conserving water via ice, based on precise data from NASA’s Lunar Reconnaissance Orbiter. In other words, future lunar dwellers may be in luck.
“If we’re right, water is going to be more accessible for drinking water, for rocket fuel, everything that NASA needs water for,” said Hayne, also of the Department of Astrophysical and Planetary Sciences.
If you can imagine standing on the surface of the moon near one of its poles, you would see shadows all over the place. Many of those tiny shadows could be full of ice.
Paul Hayne
Visiting a crater
Take a trip to Shackleton Crater on the moon’s south pole to learn about cold traps. This massive impact crater is many miles deep and measures around 13 miles in diameter.
Because of the moon’s alignment with the sun, much of the crater’s interior is perpetually in darkness, with no direct sunlight, causing temperatures to hover around minus 300 degrees Fahrenheit.
“You look down into Shackleton Crater or Shoemaker Crater, you’re looking into this vast, dark inaccessible region,” Hayne said. “It’s very forbidding.”
The craters’ forbidding nature, on the other hand, maybe important to their significance for projected lunar outposts. Scientists have long suspected that such frigid traps would be excellent for hosting ice, a precious resource that is limited on the moon but periodically delivered in great amounts when water-rich comets or asteroids collide.
“The temperatures are so low in cold traps that ice would behave like a rock,” Hayne said. “If water gets in there, it’s not going anywhere for a billion years.”
However, in their most recent study, Hayne and his colleagues sought to determine how widespread such traps are. Do they only exist in large craters or do they cover the entire moon’s surface?
To find out, the researchers used data from real-world moon observations and mathematical methods to simulate what the moon’s surface would look like on a very small scale. The answer is that it resembles a golf ball.
According to the team’s calculations, the moon’s north and south poles might have a massive number of bumps and knicks capable of hosting persistent shadows, some as small as a centimeter in diameter. The size of cold traps on the moon was previously estimated to be around 7,000 square miles, around half of what Hayne and his colleagues expected.
Mining for water
Hayne points out that his team can’t establish that these shadows contain ice pockets; the only way to do so is to dig in person or with rovers. However, the findings are encouraging, and future missions may offer much more light on the moon’s water resources.
For example, Hayne is leading the Lunar Compact Infrared Imaging System (L-CIRiS), a NASA project that will acquire heat-sensing panoramic photos of the moon’s surface near its south pole in 2022. If his findings are correct, getting the components for a hot shower on the moon just became a whole lot easier.
“Astronauts may not need to go into these deep, dark shadows,” Hayne said. “They could walk around and find one that’s a meter wide and that might be just as likely to harbor ice.”
Oded Aharonson and Norbert Schörghofer of the Weizmann Institute of Science and the Planetary Science Institute are coauthors on the new work.
