Micrometeorites collide with the moon at high speed, sending shockwaves through the lunar surface. They only need to penetrate a few inches to deposit water, and the high energy of the collision converts the molecules into water vapor. The feathers jumped into space. Most of the molecules scatter around the moon in the very thin atmosphere, while some settle back into the ground.
The lead author of the study was Mehdi Benna, a planetary scientist at NASA's Goddard Space Flight Center. He told CNN's Breakthrough "Provide a Great Piece of the Puzzle", what happens when meteorites collide with other "airless bodies" around our solar system and beyond.
It shows that water is not just trapped in the soil. According to Benna, this has implications for how future human or robotic researchers on the moon can use the resources on the ground.
The scientists believed that meteorites could raise lunar deposits. Now they know exactly
Benna, who also holds a planetary science role at the University of Maryland-Baltimore County, said that water is "globally" widespread on the moon. But we do not know much about his behavior in everyday life.
He led colleagues to sift through data assembled with the neutral mass spectrometer aboard the Lunar Atmosphere and Dust Environment Explorer (LOADEE), a robotic mission orbiting the moon.
Earlier moon probes such as Cassini and Deep Impact had shown "the existence of an active water cycle on the moon," wrote Benna and his co-authors. They decided to investigate 33 surface water flags, 29 of which were known and four were new.
The scientists knew that the water clouds corresponded to the times of the meteorite currents. And computer molecules had predicted that meteorites could trigger these water flags.
But Benna's team could actually see something that had not been confirmed before. This is "the first time it has been observed in practice," he said.
And because scientists have confirmed it on an airless body, they can now close the same process everywhere, Benna said.
Although water is widespread in the lunar soil, it is spread very thinly. The moon is pretty dry. One ton of regolith (the layer of loose soil and deposits covering solid rock at the lunar well) is just 16 ounces. of water, the amount in an average bottle of water.
The study shows that the moon is not so quiet and desolate
Studies like these show that the moon is simply a static sphere, and show us a new portrait of the moon as a rocky world living on dynamic geological and chemical processes.
Benna said he remembered looking up at the moon as a boy and thought of the distant, ancient globe as "calm and desolate."
But this study tells him, and millions of boys and girls, another story.
"What upsets me," Benna said, is that the study shows that the moon is changing and not responding to its heavenly neighborhood for decades or centuries, but "over days and even hours".
"Looks kidding," Benna said. "The moon is active."