The moon contains a lot more water than scientists had originally predicted. This, according to new research that took its data from the “orange soil” that astronaut Harrison Schmitt of Apollo 17 brought home to Earth.
The findings come from a scientific team that have been searching for water and other volatiles in volcanic glasses returned by NASA Apollo missions. In fact, in 2008, the same team reported the first evidence of the presence of water on the moon and used models to estimate just how much water was originally in the magmas before they were ejected during volcanic explosions.
“The bottom line,” said Alberto Saal, associate professor of geological sciences at Brown University, and an author on the current paper, “is that in 2008, we said the primitive water content in the lunar magmas should be similar to the water content in lavas coming from the Earth’s depleted upper mantle. Now, we have proven that is indeed the case.”
The most recent findings received a surprise helping hand from Brown University sophomore Thomas Weinreich, who in a research summer job sorted through thousands of grains from the orange soil to before he found ten that included melt inclusions – tiny globules of molten rock trapped within crystals that are found in volcanic glass deposits formed during explosive eruptions.
“It just looks like a clear sample with some black specks in it,” said Weinreich, the second author on the paper.
“Water plays a critical role in determining the tectonic behavior of planetary surfaces, the melting point of planetary interiors and the location and eruptive style of planetary volcanoes,” said Erik Hauri, a geochemist with the Carnegie Institution of Washington and lead author of the study. “We can conceive of no sample type that would be more important to return to Earth than these volcanic glass samples ejected by explosive volcanism, which have been mapped not only on the moon but throughout the inner solar system.”
“In contrast to most volcanic deposits, the melt inclusions are encased in crystals that prevent the escape of water and other volatiles during eruption. These samples provide the best window we have on the amount of water in the interior of the Moon,” said James Van Orman of Case Western Reserve University, a member of the science team.
This study also spins a new twist into the discovery of water ice detected in craters at the lunar poles of the moon. The ice had originally said to have been deposited there by comet and meteor impacts, but given the most recent findings, it could easily have made it there from within the moon itself.