Evidence of water on the moon, study says
U.S. researchers have found evidence of water on the moon by studying glass pebbles picked up by NASA astronauts more than 30 years ago.
And they speculate there may still be ice in the shaded craters at the moon's poles.
"What is important for me is it’s telling me something about the origin of the moon and the Earth and the presence of water at very early times," Alberto Saal, lead researcher and assistant professor of geological sciences at Brown University, said in a news release Thursday.
The study, published in Nature on Thursday, means "the presence of water must be considered in models constraining the moon's formation and its thermal and chemical evolution," the abstract said.
Scientists have long thought there may have been water on the moon, but have not been able to find evidence until now.
The researchers studied lunar magmas ejected from "fire fountains" on to the surface of the moon more than three billion years ago. Most of the water in the magma vaporized into space, but traces may have drifted to the moon's cold poles, where they could remain as ice in shadowed craters.
The glass beads from the magmas were bombarded with a stream of ions, and then the team analyzed the secondary ions emitted with a mass spectrometer.
"We developed a way to detect as little as five parts per million of water," said researcher Erik H. Hauri from the Carnegie Institution for Science. "We were really surprised to find a whole lot more in these tiny glass beads, up to 46 parts per million."
The scientists could not determine the precise water content of the magma, but numerical modelling suggests it contained 745 parts per million.
That's similar to the water in primitive magmas that erupted on the Earth’s sea floor.
"This suggests the very intriguing possibility that the moon’s interior might have contained just as much water as the Earth’s depleted upper mantle," Hauri said.
The researchers plan further studies of the volcanic glasses.
NASA plans new moon mission
NASA, which funded the research, is planning to send the Lunar Reconnaissance Orbiter to the moon late this year. The unmanned flight will look for evidence of water and landing sites, among other things.
NASA sent a spacecraft called the Lunar Prospector to check for water on the moon in 1998, but the mission came up dry.
The other researchers who worked on the Nature study were professors Reid Cooper and Malcolm Rutherford and graduate student Mauro Lo Cascio from Brown, and James Van Orman from Case Western Reserve University.