Geologists at the California Institute of Technology (Caltech), working with colleagues at the University of Tennessee, found structurally bound hydroxyl groups in a calcium phosphate mineral, apatite, within a basalt collected from the moon"s surface by the Apollo 14 astronauts.
"The moon, which has generally been thought to be devoid of hydrous materials, has water," said John Eiler Professor of Geology at Caltech.
To be precise, they didn't find 'water', the molecule H2O. Rather, they found hydrogen in the form of a hydroxyl anion, OH-, bound in the apatite mineral lattice. Hydroxide is a close chemical relative of water.
The lunar basalt sample in which the hydrogen was found had been collected by the Apollo 14 moon mission in 1971.