It's right there: Nasa discovers water on Moon's crater visible from Earth

The discovery comes on the back of several other observations made in the past, including by Chandrayaan-1. Here's why it is of critical importance

In one of the biggest astronomical discoveries of the decade, Nasa confirmed the presence of water on the sunlit surface of the Moon. The Stratospheric Observatory for Infrared Astronomy (SOFIA), for the first time, confirmed that water may be distributed across the moon and not just limited to cold, shadowed places. The water molecules were found on Moon's Clavius Crater, one of the largest craters visible from Earth.

Scientists believe that the majority of the water detected must be stored within glasses or in voids between grains sheltered from the harsh environment, allowing the water to remain on the lunar surface. The discovery was published in Nature Astronomy on late Monday night. 

Nasa in a teleconference said, "SOFIA has detected water molecules (H2O) in Clavius Crater, one of the largest craters visible from Earth, located in the Moon’s southern hemisphere."  In the past, scientists had detected some form of hydrogen on the lunar surface, however, they were unable to distinguish between water and its close chemical relative, hydroxyl (OH). 

“Without a thick atmosphere, water on the sunlit lunar surface should just be lost to space,” said C I Honniball, the lead author and a postdoctoral fellow at NASA’s Goddard Space Flight Center. “Yet somehow we’re seeing it. Something is generating the water, and something must be trapping it there.”\

This image from 1991 shows Earth's Moon, with its dark basaltic mare, clearly visible in great detail. (Nasa)

Why is the discovery critical?

The discovery of water, though, in a small quantity raises new questions about how water is created and how it persists on the harsh lunar terrain in a vacuum. The discovery holds critical significance as the United States sets its eyes on returning to the moon with the Artemis program. 

Water is a precious resource in deep space and a key ingredient of life as we know it. Under NASA’s Artemis program, the agency is eager to learn all it can about the presence of water on the Moon in advance of sending the first woman and next man to the lunar surface in 2024 and establishing a sustainable human presence there by the end of the decade. “We had indications that H2O – the familiar water we know – might be present on the sunlit side of the Moon,” said Paul Hertz, director of the Astrophysics Division in the Science Mission Directorate adding that this discovery challenges the understanding of the lunar surface and raises intriguing questions about resources relevant for deep space exploration.

Water is a valuable resource and the discovery opens new avenues, wherein, if it can be used then astronauts could carry less water and more equipment to the lunar surface for new scientific discoveries.

Following the Chandrayan-1 trail

For many years, researchers believed that the rocks from the moon were bone-dry and any water detected in the Apollo samples had to be contamination from Earth. All that changed in 2013, when the Moon Mineralogy Mapper (M3) instrument aboard the Indian Space Research Organisation's (ISRO) Chandrayaan-1 spacecraft remotely detected magmatic water or water that originates from deep within the moon's interior, on the surface of the moon. The latest discovery by SOFIA comes on the back of several other observations made in the past including by the Chandrayaan-1 mission. 

Moon as seen from Earth's orbit. (Nasa)

Chandrayaan-1's discovery paved the way for scientists to begin testing some of the findings from sample studies in a broader context, including in regions that are far from where the Apollo sites are clustered on the near side of the moon. “Prior to the SOFIA observations, we knew there was some kind of hydration,” Nasa quoted Honniball as saying. “But we didn’t know how much, if any, was actually water molecules – like we drink every day – or something more like drain cleaner,” she added. 

The path-breaking SOFIA flight 

Flying at altitudes of up to 45,000 feet, SOFIA, a modified Boeing 747SP jetliner with a 106-inch diameter telescope offers a new means of looking at our natural satellite. The telescope offers a new vantage point in the cosmos as it reaches above 99 per cent of the water vapor in Earth’s atmosphere to get a clearer view of the infrared universe. It is mostly used to look at distant, dim objects such as black holes, star clusters, and galaxies.

According to NASA, using its Faint Object infraRed Camera for the SOFIA Telescope (FORCAST), the plane was able to pick up the specific wavelength unique to water molecules, at 6.1 microns, and discovered a relatively surprising concentration in sunny Clavius Crater. 

The discovery holds critical significance as the United States sets its eyes on returning to the moon. (Nasa Artemis)

According to scientists, several developments could have led to the storage of water in the nodes, Micrometeorites raining down on the lunar surface, carrying small amounts of water, could deposit the water on the lunar surface upon impact. Another possibility is there could be a two-step process whereby the Sun’s solar wind delivers hydrogen to the lunar surface and causes a chemical reaction with oxygen-bearing minerals in the soil to create hydroxyl. Scientists are also looking to explore how the water gets stored on the surface. One argument is that the water could be trapped into tiny beadlike structures in the soil that form out of the high heat created by micrometeorite impacts. Another possibility is that the water could be hidden between grains of lunar soil, they argue. 

SOFIA’s in its follow-up flights will now look for water in additional sunlit locations and try to learn more about how the water is produced, stored, and moved across the Moon.