When asteroids or meteors crash into the moon, the collisions send fragments of the lunar surface flying into the air, heated to molten temperatures by the impact. Under these extreme conditions, silicate particles come together to form tiny glass beads, writes Live Science’s Ben Turner. Now, scientists say they've found water stored in these glass beads in samples returned from the moon.
Vast amounts of glass beads, tucked away in lunar soil, could hold up to 300 billion tons of water, researchers estimate.
“This work adds to the growing consensus that the moon is more water-rich than previously thought,” Ian Crawford, a planetary scientist and astrobiologist at Birkbeck, University of London, who did not participate in the study, tells the Guardian’s Ian Sample.
The findings, published Monday in the journal Nature Geoscience, point to a potential source of water for humans to use on future lunar missions.
“Water is the most sought-after commodity for enabling sustainable exploration of planetary surfaces,” Mahesh Anand, a co-author of the study and a planetary scientist at the Open University in England, tells Inverse’s Doris Elín Urrutia. “Knowing how water is produced, stored and replenished near the lunar surface would be very useful for future explorers to extract and [utilize] it.”
“For future in-situ resource planning, this is a big step forward that points the way to a resource that has fairly high contents of water,” Craig O’Neill, a geophysicist and planetary scientist at the Queensland University of Technology in Australia who did not contribute to the study, tells Genelle Weule of the Australian Broadcasting Corporation (ABC).
Scientists first detected signs that water might exist on the moon in the 1990s: Data from NASA’s Clementine orbiter suggested the moon’s shadowed region might hold ice, and NASA’s Lunar Prospector mission found evidence hinting at the existence of ice at the poles. In 2020, data from the space agency’s Strategic Observatory for Infrared Astronomy confirmed water existed in lunar soil on the sunlit side. As evidence has piled up over the years, scientists today have “little doubt” that most of the moon’s surface holds water in some form, the authors write.
The examined glass beads, which ranged from about 50 micrometers to 1 millimeter in size, came from a lunar soil sample retrieved by China’s Chang’e 5 mission to the moon in 2020. After the beads were blasted into existence, scientists theorize that water formed inside of them via solar wind, a flow of particles from the sun. Hydrogen from this influx could have combined with oxygen atoms in the beads to form water.
“The hydrogen isotope composition at the rim [of the beads] is similar to the hydrogen isotope composition of solar wind,” Hejiu Hui, a study co-author and planetary geochemist at Nanjing University in China, tells Inverse. “This similarity suggests the water at the rim derived from the solar wind.”
Water may have diffused in and out of the beads every few years, contributing to a form of water cycle on the moon, according to the researchers’ analysis.
“Geophysical models have suggested a very similar sort of process; this is just one of the first demonstrations of it using samples and measured data,” Marc Norman, a geologist and geophysicist at the Australian National University, tells the ABC.
Understanding how water is stored on the moon could eventually help astronauts use it for drinking or fueling rockets, Hui says to CNN’s Jackie Wattles. “This water can be released by just simply heating these glass beads,” he tells the publication.
But Norman cautions that accessing the water may not be so simple: “The beads are small, and there’s typically a modest amount of them in the soil,” he tells the ABC. “Extracting them on an industrial scale for in-situ resource utilization—at least at this point in time—may be overstating their potential significance.”