Water Trace Found in Old Lunar Samples From Apollo

Researchers announced the discovery of tiny amounts of water in the moon rocks brought to Earth by the Apollo missions, which in turn could invalidate the current theory of how our Moon was formed in the first place. University of Michigan researchers and colleagues analyzed mineral grains from the lunar highlands, a region that is assumed to represent the original crust that crystallized from a mostly molten young moon. According to the researchers, the result implies that the lunar core contained water during the molten stage before the crust solidified, which doesn't fit with the dominant theory that the moon formed from the debris generated during a giant impact with the proto-Earth and any water in lunar rocks was added after its formation by smaller meteorite impacts or solar wind.

"Because these are some of the oldest rocks from the moon, the water is inferred to have been in the moon when it formed," UM researcher Youxue Zhang said. "That is somewhat difficult to explain with the current popular moon-formation model, in which the moon formed by collecting the hot ejecta as the result of a super-giant impact of a martian-size body with the proto-Earth. Under that model, the hot ejecta should have been degassed almost completely, eliminating all water."

The scientists used a method called fourier-transform infrared spectroscopy to re-analyze the water content by determining hydroxyl groups in the old samples . The traces found amount to a water content of just 6 parts per million in the lunar material.

"We are able to detect those hydroxyl groups in the crystalline structure of the Apollo samples," said Hejiu Hui, an author from the University of Notre Dame.

The new findings imply that the early moon was somewhat wet and that water was not lost completely during the moon's formation, the researchers said.