Moon's Glass Beads Hold Billions of Tons of Water

moon beads — The ability to source water without hauling it to the moon will be critical to allowing people to live and work there in the future. LAURENT EMMANUEL/AFP/Getty Images

We sometimes forget water has a recipe: one atom of oxygen, two atoms of hydrogen. All water was made somehow, and here on Earth, the same water has been knocking around this old planet for billions of years, thanks to our water cycle.

But water exists in other places, too — anywhere oxygen and hydrogen atoms have the chance to find one another. The trick is, if other objects in space are going to keep their water, they've got to have a way to hold onto it. Not everybody has a fabulous atmosphere like Earth.

Surprisingly, Chinese researchers have recently discovered that our moon has a vast store of water — probably upwards of 330 billion tons (300 billion metric tons) of it — hidden away under the lunar soil.

Water Beads Called Microtektites

In the March 2023 edition of the journal Nature Geoscience, the researchers report that glass beads containing tiny droplets of water can be found all over the moon. These beads were collected in December 2020 by China's Chang'e-5, a robotic spacecraft sent to the moon's surface to collect rock and soil.

In collecting these samples, researchers found that the surface of the moon is uniformly littered with tiny glass beads called microtektites. These spherical grains measuring less than a millimeter across were created by the meteorites, big and small, that are constantly bombarding the moon's surface, exploding molten chunks of lunar crust far into the air. While hanging out in a red hot soil plume, some of the material cooled into tiny silicate spheres.

While drifting through the thin lunar atmosphere, the microtektites come into contact with solar winds. From the name, you might assume solar winds to be warm and pleasantly mild. They're actually relentless blasts of plasma as hot as 1,800,032 degrees Fahrenheit (1 million degrees Celsius), made up of energized electrons and protons screaming through space at 560 miles per second (900 kilometers/second). This "wind" contains, among other things, hydrogen nuclei. Lunar soil contains some oxygen, and when it combines with the hydrogen in the solar wind, it creates water, and these little glass beads absorb tiny bits of this water before dropping back to the surface of the moon.

Can the Water Be Harvested?

In short, yes. The water is not locked in these microtektites indefinitely. The researchers suggest the spheres are covered over in lunar dust, where water diffuses in and out of the beads over the course of years, creating something a bit like a water cycle on the moon. Releasing the water would be easily done by collecting the spheres, heating them up and collecting the resulting water vapor.

The 265 trillion liters (70 trillion gallons) or so of water involved is not going to support a city on the moon, and collecting the beads and harvesting their water will be a difficult task. But the beads interest scientists because they represent relatively ready access to water that might eventually help future astronauts in emergency situations, and for things such as drinking water or creating rocket fuel.