Scientists Just Reported The First Unambiguous Detection of Water on The Moon

 It's official. There's water on the Moon.

We've thought that there was for over a decade, supported detections described back in 2009, but there was room for interpretation within the wavelengths used. Now, employing a different wavelength unique to water, scientists report the primary unambiguous detection.

Those 2009 conclusions were apparently on the money.

The ambiguity arose because the 2009 detections were made within the 3-micrometre infrared band. At this wavelength, there have been two possibilities - water, or another hydroxyl compound comprising hydrogen and oxygen.

Led by astronomer Casey Honniball of the NASA Goddard Space Flight Centre, a team of scientists decided to appear into the wavelength that would confirm or overturn those findings. The 6-micrometre infrared band should show a line which will only be created by two hydrogen atoms and one oxygen atom - what's called the H-O-H bend vibration.

But actually making an unambiguous detection in this band is difficult. It requires the employment of the Stratospheric Observatory for Infrared Astronomy (SOFIA), a special, one-of-a-kind telescope that's flown during a plane above the majority of Earth's atmosphere.

"SOFIA is that the only current and planned observatory capable of those observations," Hannibal told ScienceAlert.

"Current lunar spacecraft don't have instruments which will measure at 6 micrometres, and from the bottom, Earth's atmosphere blocks 6-micron light, so it can't be done from ground-based observatories. SOFIA flies above 99.9 per cent of the Earth's water vapour, which allows 6-micrometre light to withstand and be observed. and fortuitously SOFIA's FORCAST instrument can make 6-micrometre measurements and appearance at the Moon."

Using FORCAST, the team carefully studied a vicinity during which the 3-micrometre detections had been made - high southern latitudes, around the pole. There, they found the emission line they'd been hoping for - that unique signature that would only be created by the H-O-H bend vibration.

Based on their detections, the team estimates water abundances of around 100 to 400 parts per million - in keeping with 3-micrometre detections made by the Moon Mineralogy Mapper.

Of course, there aren't any liquid lakes sloshing around on the lunar surface, and any frozen water would sublimate as soon because the sunlight hit it. But there are multiple ways the Moon could still be harbouring surface water.

"We mainly think the water is in glass," Hannibal said.

"When a micrometeorite impacts the Moon, it melts some lunar material, which quickly cools and forms a glass. If there's water already present, formed during or delivered during the impact, a number of the water will be captured within the structure of the glass while it cooled."

In a separate paper led by astronomer Paul Hayne of the University of Colorado Boulder, scientists explored another possibility - regions of permanent shadow in polar craters. At high latitudes, high crater rims create regions that sunlight never touches.

In these spots, temperatures never reach above approximately -163 degrees Celsius (-260 degrees Fahrenheit), creating cold traps that would harbour hidden patches of water ice.

Using data from NASA's Lunar Reconnaissance Orbiter, Hayne and his colleagues calculated that there can be the maximum amount as 40,000 square kilometres (15,000 square miles) of such permanently shadowed surface. And 60 per cent of that's at the South Pole.

"The temperatures are so low in cold traps that ice would behave sort of a rock," Hayne said. "If water gets in there, it is not going anywhere for a billion years."

Both papers have important implications for future lunar missions. NASA is getting to establish a lunar base as a part of the Artemis mission; if an abundant source of water is often found nearby, lunar residents could make use of it for drinking, for growing crops, even splitting it using electrolysis to get hydrogen for burster.

But we'd like to induce an improved picture of where the water may well be, and the way much is there. The work of Haynes' team will help see where to look; the work of Honniball's team gives us the how. All we want now could be the telescope time.

"We are granted two more hours on SOFIA and are requesting a further 72 hours," Hannibal said. "With more observations, we are going to be ready to characterise the behaviour of water across the lunar surface and understand its source, where it resides, and if it moves around the lunar surface."