PARIS • Future astronauts headed to the Moon may have an easier time finding water and digging up ice than had been thought.
In a paper published in Monday's Nature Astronomy, a team of scientists used Sofia, an infrared telescope mounted inside a 747 jumbo jet, to make observations that showed unambiguous evidence of water on parts of the Moon where the sun shines.
"This discovery reveals that water might be distributed across the lunar surface and not limited to the cold shadowed places near the lunar poles," said Dr Paul Hertz, director of the astrophysics division at the National Aeronautics and Space Administration (Nasa).
Although that water could be difficult to collect by astronauts, another group of researchers reported on Monday that in addition to big, frigid, deep and potentially treacherous craters in the Moon's polar regions, smaller and shallower depressions in the same areas may also be cold enough to hold on to water ice for millions, if not billions, of years.
These small, water ice deposits could be a "real game changer", said Dr Paul Hayne, a professor of astrophysical and planetary sciences at the University of Colorado, who led that research.
"It could make it much more accessible to future astronauts and rover missions."
Such ice might not only provide water for future astronauts to drink, but water molecules can also be broken apart into their constituent hydrogen and oxygen atoms.
The oxygen would give the astronauts something to breathe.
Hydrogen and oxygen can also be used as rocket propellant for trips home to Earth or even some day to Mars and beyond.
That is of interest to Nasa, which is planning a human mission to the Moon in 2024 and wants to build a sustainable presence there by the end of the decade to prepare for onward travel to Mars.
Dr Jacob Bleacher, chief exploration scientist for Nasa's Human Exploration and Operations Mission Directorate, said it was crucial to find out more about where the water came from and how accessible 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.
"Any time 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."
One of the new studies was able to "unambiguously" distinguish the spectral fingerprint of molecular water in a sunlit area, said lead author Casey Honniball, of the Hawaii Institute of Geophysics and Planetology.
Using data from the airborne telescope, researchers used a more precise wavelength than had been used before - six microns instead of three.
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 (355ml) bottle of water within a cubic metre of volume of lunar soil," Dr Honniball said at a Nasa press conference.
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.
In the second study, researchers looked at the Moon's polar regions, where water ice has been detected in lunar craters that never see sunlight.
Nasa in 2009 found water crystals in a deep crater near the Moon's southern pole.
But the new study found evidence of billions of micro-craters that could each cradle a minuscule amount of ice.
The authors say this could mean that approximately 40,000 sq km of the lunar surface has the capacity to trap water.
The micro-craters should be as cold - around minus 160 deg C - as the larger, kilometre-scale lunar hollows, Dr Hayne said, adding that there are "tens of billions" of them.
Samples from these cold traps could tell us more about how the Moon - and even Earth - got its water, Dr Hayne said, perhaps providing evidence of water delivered by asteroids, comets and the solar wind.
NYTIMES, AGENCE FRANCE-PRESSE
