According to NASA, there are up to 231 million tons of water ice on the moon that could help supply lunar colonists. The water could even become an affordable form of rocket fuel if you split it into oxygen and hydrogen and liquefy the gases.

For a long time it was unclear how much water there is on the moon, where exactly these reserves are stored and how we can access them. There is not yet an answer to all of these questions. But two new studies that have appeared in the journal “Nature Astronomy” at least suggest that water on the moon is not quite as hidden as expected.

So far, researchers have assumed that water in regions of the moon that are permanently covered by shadow and protected from solar radiation, such as large Craters has the best chance of remaining stable. But now scientists from the Stratospheric Observatory for Infrared Astronomy (SOFIA) of NASA and the German Aerospace Center are reporting on the detection of water molecules that are near the 231 Kilometers of Clavius ​​Crater were exposed to sunlight.

“This is the first time that we can say with certainty that there are water molecules on the lunar surface,” says Casey Honniball from NASA’s Goddard Space Flight Center and lead author of the SOFIA study. The SOFIA observations suggest that the water molecules are built into the structure of glass beads and thus withstand solar radiation. “We would expect the amount of water to increase as we approach the poles,” says Honniball. “But at SOFIA we observed the opposite.” The pearls were found at a latitude closer to the equator, although that is probably not a nationwide phenomenon.

The SOFIA aerial observatory was modified from a modified one Boeing 747 that flies through the atmosphere at high altitudes. In this way, the view of her 9-foot telescope, with which she observes objects in space, is only minimally disturbed by the earth’s atmosphere, which contains water.

The glassy water features on the moon have already been shown in a 1969 discovered lunar mineralogy investigation carried out by balloon observatory. However, they were neither reported nor published. “Maybe they didn’t realize what a great discovery they actually made,” says Honniball. It is true that the amount of water contained in the glass beads is too small to be useful for humans. But it is possible that the concentration is higher in other regions. More importantly, the results show the possibility of a “moon water cycle” that could replenish the water reserves on the moon.

The smallest shadows The second study could be even more relevant to NASA’s immediate lunar exploration plans. Their results suggest that the water ice reserves of the earth’s satellite are maintained in so-called micro-cold traps with a diameter of up to one centimeter. New 3D models created using thermal infrared and optical images from NASA’s Lunar Reconnaissance Orbiter show that temperatures in these micro-traps are low enough to keep the water ice intact. They possibly contain ten to 20 percent of the water stored in all permanently shadow-covered lunar regions over a total area of ​​approximately 40. square kilometers, mainly in the polar regions.

“Instead of just a handful of large cold traps in ‘craters by name’, there is a whole galaxy of tiny cold traps spread across the entire polar region,” says Paul Hayne of the University of Colorado in Boulder. “Micro cold traps are much more accessible than larger, permanently shaded regions. Instead of designing missions that venture deep into the shadows, astronauts and rovers could stay in the sunlight while they extract water from micro-cold traps, ”says the planetary scientist and lead author of the study. There could be hundreds of millions or even billions of these places scattered across the lunar surface.

More data raises more puzzles There is still no clear explanation of how this water-bearing glass was formed. According to Honniball, they likely came from meteorites that either created or supplied the water on impact. They could also be the result of ancient volcanic activity.

The SOFIA study also cannot explain why the distribution of glass depends on latitude or how it could change over a full lunar cycle, says the planetary geologist Clive Neal from Notre Dame University, who was not involved in either study. We may not have to wait long for these data, however.

In the run-up to the Artemis missions, which will also bring astronauts back to the surface of the moon, NASA’s robotic missions will also examine the water ice content on the moon. For example, the Viper rover, whose launch is planned for 2022, should keep an eye out for underground water ice. Given the new evidence, NASA might decide to change Viper’s goal a bit to also examine surface water, glass structures under the sun, and how well the microcold traps are preserving the water ice. Neal also suggests that a lunar exosphere monitoring system would be very useful to unravel the history of water on the moon and how a possible lunar water cycle leads to stable or unstable water on the surface.

(vsz)