WASHINGTON - Parts of the moon's interior contain as much water as the upper mantle of the Earth - 100 times more of the precious liquid than measured before, according to a new study.

Under a joint research project of Case Western Reserve University, Carnegie Institution for Science, and Brown University, the scientists discovered water along with volatile elements in lunar magma trapped inside of crystals that are trapped inside of tiny volcanic glass beads returned to Earth by Apollo 17 in 1972.

The discovery, to be published Friday in the Science journal, challenges assumptions of how the moon was formed and the origin of frozen water at the lunar poles.

"These samples provide the best window we have to the amount of water in the interior of the Moon," said James Van Orman, professor of geological sciences at Case Western Reserve and co-author of the paper. "The interior seems to be pretty similar to the interior of the Earth, from what we know about water abundance."

In fact, the researchers found the concentrations of water and volatile elements including fluorine, chlorine and sulfur in lunar magma are nearly identical to concentrations in solidified magma from primitive terrestrial mid-ocean ridges on Earth. 

The discovery strengthens the theory that the moon and Earth have a common origin but forces scientists to reconsider the current theory of the process: that a huge impact in Earth's early history ejected material into orbit that became the moon.   

Part of the origin theory says that water and other volatile elements and compounds were depleted due to the heat and violence of the impact.