Hopes flow from water find for lunar missions

Confirmation of its presence on moon expands exploration scope, experts say

Signs of water in the sun-baked lunar soil and in dark craters have significant implications for future space missions and exploration, scientists say.

Alice Gorman, from the College of the Arts, Humanities and Social Sciences at Flinders University in South Australia, said the new findings confirm "something we didn't know for sure: The moon has actual water and not just various other oxygen/hydrogen compounds".

She said these results have implications for how humans might extract water to sustain a habitation or make fuel. "Permanently shadowed regions only occur on the moon, Mercury and the dwarf planet Ceres," she said.

Scientists have always thought the moon to be waterless. But in recent years studies have shown parts of the moon's surface could contain water, especially in deep, permanently shadowed craters at its poles.

Two papers published in the journal Nature Astronomy on Monday presented further evidence that the moon does contain water. The findings will have significant implications for future missions to the moon and beyond.

In one paper, data gathered by scientists from NASA's Stratospheric Observatory for Infrared Astronomy, or SOFIA, detected the unique signature of water (H2O) at the moon's high southern latitudes.

SOFIA is a 2.7-meter telescope mounted on a modified 747SP aircraft. Its unique capability allows observations in infrared without the use of space-based facilities.

Another paper measured the moon's permanently shadowed areas known as cold traps. Because of these cold traps, the authors suggest that around 40,000 square kilometers of the lunar surface has the capacity to trap water.

The findings indicate water is produced or delivered on the moon by various processes, which may have implications for future lunar missions.

Previous research had reported signs of hydration on the lunar surface, particularly around the south pole. However, these detections were based on a spectral signature that cannot discriminate between H2O and hydroxyl bound in minerals.

Spectral signature

Casey Honniball, a NASA postdoctoral program fellow at the agency's Goddard Space Flight Center and researcher at the University of Hawaii at Manoa, said researchers were able to detect, through SOFIA, a spectral signature of H2O that is not shared with other hydroxyl compounds.

They found that water is present at high southern latitudes in abundances around 100 to 400 parts per million H2O.

The study suggests that the detected water is probably stored in glass or between grains on the lunar surface that protect it from the harsh environment.

Paul Hayne, assistant professor in the laboratory of atmospheric and space physics at the University of Colorado Boulder in the US, together with colleagues, examined the distribution of permanently shadowed areas where water could be captured and remain permanently frozen.

The authors assessed a range of possible sizes for cold traps and found that small "micro" cold traps are hundreds to thousands of times more numerous than larger cold traps, and they can be found at both poles.

Rebecca Allen, project coordinator for Swinburne University's Space Office in Melbourne, Australia, said the two papers provide critical information for future space exploration missions that plan to utilize the moon's water to create fuel and other resources.

Professor Fred Watson, an astronomer-at-large from the Australian Department of Industry, Science, Energy and Resources, said: "We have known for more than a decade that the moon's polar regions contain oxygen and hydrogen atoms bonded together either as hydroxyl (OH) or water (H2O).

"Now these assumptions have received strong support from observations made with SOFIA."

The possibility of water reservoirs on the moon is of great interest in upcoming lunar exploration missions, he said.

Nick Tothill, a senior lecturer in physics at Western Sydney University, said:"These papers tell us that there really is water ice on the moon, and it's probably widespread over both polar regions-with a bit more in the south.

"This in turn tells us how and where to look for water on the moon, with either robot or human explorers."