A research team including Prof. James A. Van Orman finds traces of water in lunar volcanic glasses
One of the most striking features of the lunar samples returned by the Apollo missions is their depletion in volatile elements–particularly hydrogen, which appeared to be completely absent. Volatile elements are thought to have been stripped away during the Moon-forming event, a giant collision between the proto-Earth and another proto-planetary body. Now, for the first time, indigenous hydrogen has been detected in primitive lunar volcanic glass beads by a team of researchers from Brown University, the Carnegie Institution for Science, and Case Western Reserve University. The concentration of hydrogen in the samples is very small, less than 50 parts per million-but the distribution of hydrogen and other volatile elements across one of the glass beads indicates that a substantial fraction of the hydrogen, 90% or more, was degassed during eruption. Although the pre-eruptive abundance of hydrogen is not precisely constrained, the best match to the volatile profiles indicates that the mantle source of the lunar volcanic glasses had about the same concentration of water as Earth’s depleted upper mantle. In other words, at least one part of the Moon retained some hydrogen during or shortly after the Moon’s formation-and possibly quite a bit of it. Read more about this in an article recently published in the Cleveland Plain Dealer.
Saal A.E., Hauri E.H., Lo Cascio M., Van Orman J.A., Rutherford M.C., Cooper R.F. (2008) Volatile content of lunar volcanic glasses and the presence of water in the Moon’s interior. Nature 454, 192-195.