Moon Has More Water Than Previously Thought in Challenge to View of Origin
The moon has more water than scientists once thought, casting doubt on theories of its creation, according to a study.
Scientists measured seven samples of magma trapped as “melt inclusions,” within crystals, according to a paper in the journal Science. The water content of the lunar magma was 100 times higher than previous studies have suggested.
Lower quantities of water and volatile compounds on the moon, when compared with the Earth and other inner planets of the solar system, have long been taken as evidence the moon formed during a giant impact that had enough energy to create seas of magma, according to the Carnegie Institution’s Erik Hauri, the study’s lead author. Today’s finding challenges that view, he said.
“If our samples are representative of the entire moon, this is basically the best way to calculate how much water’s on the moon,” Hauri said. “And what are the chances that the first seven samples look like Earth?”
The findings suggest that the impact from a Mars-sized body that formed the moon was either much hotter or much cooler than previously thought. If the moon impact was cooler, then some material including water wasn’t molten and was locked in the lunar interior.
If there was more energy, then the rocks boiled and created a temporary atmosphere, Hauri said. While the atmosphere would have been dense and short-lived, it might have allowed the still-forming Earth and moon to exchange water.
“The presence of water tells you how much potential it has to sustain life,” Hauri said.
The National Aeronautics and Space Administration discovered water on the moon by crashing a Centaur rocket into a crater called Cabeus. At the time, scientists involved in the discovery suggested the water was left by impacts from meteors or comets. This study may mean that some of the ice came from eruptions from the moon’s interior.
In addition, the Cabeus impact suggested there were 1 billion gallons of water on the moon. Today’s study indicates that there may be 1 billion Cabeus craters’ worth of water, Hauri said. The method could be expanded to study water content on other planets, Hauri said.
The melt inclusions, which are used to estimate water content on Earth, were discovered in a sample by Thomas Weinreich, an undergraduate at Brown University. The melt inclusions are about the size of a human hair.
The research was sponsored by NASA and the Carnegie Institution for Science, which is based in Washington D.C.
To contact the editor responsible for this story: Reg Gale at email@example.com.