Moon Richer in Water Than Once Thought

There could be even more water on the Moon than previously thought, according to two studies published Monday that raise the possibility that astronauts on future space missions may find refreshment — and possibly even fuel — on the lunar surface.

The Moon was thought to be bone dry until around ten years ago when a number of observations suggested that our closest celestial neighbor had evidence of water ice in permanently shaded craters in its polar regions, reports AFP.

Two new studies published in Nature Astronomy on Monday indicate that water may be much more common, including the first evidence that it is present even in more easily accessible sunlit areas.

If this water could be collected, it could allow astronauts traveling to the Moon and beyond access to drinking water. They would also be able to break the molecules into rocket fuel.

This is of particular interest to NASA, which is preparing a human mission to the Moon in 2024 and aims to create a permanent footprint there by the end of the decade to prepare for its path to Mars.

The new study was able to "unmistakably" discern the spectral fingerprint of molecular water in a sunlit region, according to lead author Casey Honniball of the Hawaii Institute of Geophysics and Planetology.

“If we find the water is abundant enough in certain locations we may be able to use it as a resource for human exploration,” Honniball, who is also a postdoctoral fellow at NASA’s Goddard Space Flight Center, told AFP.

Previous research has found traces of water on the sunlit surface — but they have not been able to differentiate between water ( H2O) and hydroxyl, a molecule made up of one hydrogen atom and one oxygen atom that is a natural drain cleaner on Earth.

Using data from the Airborne Telescope of the Stratospheric Observatory for Infrared Astronomy (SOFIA), researchers used a more accurate wavelength than was traditionally used—6 microns instead of 3.

They found a water concentration of about 100 to 400 parts per million at Clavius crater, one of the largest to be visible from Earth.

“That’s roughly equivalent to a 12 ounce (350 millilitre) bottle of water within a cubic meter of volume of lunar soil,” Honniball said in a NASA press conference.

These are not “puddles of water”, she stressed, but scattered molecules that do not form ice or liquid water.

Researchers believe they originate from solar winds or micro-meteorites and think they might either be trapped in beads of glass or within the grains of the lunar surface to protect them from the harsh atmosphere.

– ‘Tiny shadows’ –

For the second report, researchers looked at the polar regions of the Moon, where water ice had been found for lunar craters that had never seen sunlight.

NASA discovered water crystals in a deep crater near the southern pole of the Moon in 2009.

But the new study found proof of billions of micro-craters that could give each cradle a tiny amount of ice.

“If you were standing on the Moon near one of the poles, you would see a whole ‘galaxy’ of little shadows speckled across the surface,” said lead author Paul Hayne of the Department of Astrophysics at the University of Colorado.

“Each of these tiny shadows — most of them smaller than a coin — would be extremely cold, and most of them cold enough to harbour ice.”

This “suggests that water could be much more widespread on the Moon than previously thought”, Hayne said.

The authors suggest that this may mean that approximately 40,000 km2 of the lunar surface has the potential to trap water.

They were able to recreate the size and distribution of these small craters using high-resolution images and lunar temperature measurements taken from NASA's Lunar Reconnaissance Orbiter.

The micro-craters should be as cold — around -160 degrees Celsius — as the larger, kilometre-scale lunar hollows, Hayne said, adding that there are “tens of billions” of them.

– Deep space exploration –

Samples from these cold traps might tell us all about how the Moon — and even the Earth — received its water, Hayne said, maybe including evidence of water from asteroids, comets, and solar wind.

Jacob Bleacher, Chief Exploration Scientist at NASA's Human Exploration and Operations Directorate, said it was important to find out more about where the water comes from and how open it is.

“Water is extremely critical for deep space exploration. It’s a resource of direct value for our astronauts,” he told reporters, adding it was heavy and therefore expensive to take from Earth.

“Anytime we don’t need to pack water for our trip, we have an opportunity to take other useful items with us, for instance payloads to do more science.”