There may be far more water on the moon than previously thought, according to two studies published on Monday, which raised the intriguing prospect that astronauts on future space missions could find refreshment – and perhaps even fuel – on the moon’s surface.
It was assumed that the moon was bone dry until about a decade ago, when a series of finds suggested that our nearest celestial neighbor has traces of water trapped in the surface.
Two new studies published in Nature Astronomy on Monday suggest that there may be much more water than previously thought, including ice stored in permanently shady “cold traps” in polar regions of the moon.
Previous studies have found indications of water by scanning the surface – but these could not distinguish between water (H2O) and hydroxyl, a molecule consisting of a hydrogen atom and an oxygen atom.
But a new study provides further chemical evidence that the moon holds molecular water, even in sunlit areas.
Using data from the airborne telescope of the Stratospheric Observatory for Infrared Astronomy (SOFIA), scientists scanned the moon’s surface with a more accurate wavelength than previously used – six microns instead of three.
This allowed them to “unambiguously” distinguish between spectral fingerprints of molecular water, said co-author Casey Honniball of the Hawaii Institute of Geophysics and Planetology.
Scientists believe the water may be trapped in glass beads or another substance that protects it from the harsh lunar environment, Honniball told AFP, adding that further observations would help better understand where the water may have come from and how it keep.
“If we find that water is plentiful in certain places, we may be able to use it as a resource for human exploration,” Honniball said.
“It could be used as drinking water, breathable oxygen and rocket fuel.”
Another study looks at areas of the Moon’s polar regions where water ice is thought to be trapped in lunar craters that never see sunlight.
Large caves had previously been discovered – in 2009 NASA found water crystals in a deep crater near the Moon’s south pole.
But the new study found evidence of billions of microcraters, each capable of rocking a small amount of water ice.
“If you stood on the Moon near one of the poles, you would see an entire ‘galaxy’ with small shadows dotted across the surface,” said lead author Paul Hayne of the Department of Astrophysics at the University of Colorado.
“Each of these tiny shadows – most smaller than a coin – would be extremely cold, and most of them were cold enough to carry ice.”
This “suggests that water may be much more prevalent on the moon than previously thought,” Hayne told AFP.
The authors say that this may mean that approx. 40,000 km2 of the moon’s surface has the capacity to capture water.
They were able to reconstruct the size and distribution of these small craters using high-resolution images and lunar temperature measurements taken from NASA’s Lunar Reconnaissance Orbiter.
These micro-craters are distributed at both poles and should be as cold – around -160 degrees Celsius – as the larger lunar cuts on a mileage scale, Hayne told AFP.
And there are “tens of thousands of billions” of them, Hayne said, compared to a few hundred larger cold traps.
Scientists hope samples from these cold traps could tell us more about how the Moon – and even the Earth – got its water, he said, perhaps providing evidence of water supplied by asteroids, comets and the solar wind.
But they also present a potential practical resource for astronauts, both on the moon and for a human mission to Mars.
NASA, which plans to establish a space station in the lunar orbit called the Gateway, predicts that ice excavated from the Moon’s south pole may one day supply drinking water.
They could also split the molecules apart to create rocket fuel for a further journey.