Moon's Water May Have Originated in Proto-Earth

The water found in ancient Moon rocks could have originated from the proto-Earth, surviving the massive collision that resulted in the formation of the Moon. Such are the results of one study presented at the European Planetary Congress in London on Monday.

Led by Jessica Barnes of the Department of Physical Sciences at Open University, the study focused on the amount of water contained in the lunar rocks collected during the Apollo missions. In particular, the researchers examined the water present in the calcium phosphate mineral apatite found in the specimens.

"These are some of the oldest rocks we have from the Moon and are much older than the oldest rocks found on Earth," Barnes explained. "The antiquity of these rocks make them the most appropriate samples for trying to understand the water content of the Moon soon after it formed about 4.5 billion years ago and for unravelling where in the Solar System that water came from."

Based on their observations, Barnes and her colleagues determined that the lunar rocks contain appreciable amounts of water locked into the apatite's crystal structural.

Furthermore, by measuring the hydrogen isotopic signature of the water in these ancient rocks, the team of researchers were able to identify the water's likely source or sources.

"The water locked into the mineral apatite in the Moon rocks studied has an isotopic signature very similar to that of the Earth and some carbonaceous chondrite meteorites," Barnes explained. "The remarkable consistency between the hydrogen composition of lunar samples and water-reservoirs of the Earth strongly suggests that there is a common origin for water in the Earth-Moon system."

The research was funded by the UK Science and Technologies Facilities Council.