Oct. 26 (UPI) -- Water ice may be more abundant on the moon's surface than previously thought.
New research, published Monday in the journal Nature Astronomy, suggests tiny patches of ice may be hiding inside lunar shadows as a small as a penny.
"If you can imagine standing on the surface of the moon near one of its poles, you would see shadows all over the place," Paul Hayne, an assistant professor of astrophysical and planetary sciences at the University of Colorado, said in a news release. "Many of those tiny shadows could be full of ice."
Hayne and his colleagues suggest many of the moon's smallest shadows are permanent. Scientists predict many of these darkened pockets of the lunar surface, or "cold traps," haven't been hit with a ray of sunlight in billions of years.
"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.
For a bigger example of a cold trap, the study's authors looked to Shackleton Crater, a massive depression on the moon's southern pole. Because much of crater remains permanently darkened, temperatures inside the 13-mile-wide depression remain a steady minus 300 degrees Fahrenheit all year long.
"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."
To see how common cold traps are, researchers collected a wealth of data on the contours of the lunar surface and used models to simulate what the moon looks like at small scales. Their analysis showed the lunar surface is a lot like a golf ball, covered in tiny dimples.
The models showed many of these tiny bumps, ridges and crests are capable of keeping small portions of the lunar surface in permanent shadow. Though simulations suggest most of the moon's cold traps measure no more than a centimeter wide, they combine to create 7,000 square miles of permanent shadow.
Scientists can't be sure that these tiny cold traps hold water ice. To find out, a lunar mission will be necessary.
The finding was announced the same day NASA confirmed water molecules on the sunlit surface of the moon.
The discovery, researchers said, needs to be confirmed -- the atmosphere of the moon is so thin that water molecules should be quickly lost to space, so how they would remain on the surface is unknown.
But finding water resources will be essential to establishing a human presence on the moon, they said.
If the cold traps identified by Hayne and his colleagues do indeed hold water, and water molecules are found across the sunlit side of the moon, NASA may have more flexibility in where they can base their human missions.