A group of scientists at the Carnegie Institution's Geophysical Laboratory have found that the water content in the interior of the Moon is much higher than previous studies have shown.
The new findings suggest that the hot magma from when the Moon first began to form caused water to be preserved and then it spread around in its interior.
"For over 40 years we thought the Moon was dry. Recently, scientists detected water from Apollo samples on the order of 46 parts per million. We studied two other Apollo samples and a lunar meteorite using secondary ion mass spectrometry (SIMS), which can detect elements in the parts per million range. We combined the measurements with models that characterize how the material crystallized as the Moon cooled. We found that the minimum water content ranged from 64 parts per billion to 5 parts per million -- at least two orders of magnitude greater than previous results." Francis McCubbin, Lead author of the study, explained.
It has always been believed that the Moon was formed when a Mars-sized object hit the Earth, ejecting material that eventually coalesced into the natural satellite. Two Moon samples studied by the scientist group helped them determine that water was present on the Moon early in its formation from the cooling and crystallization of the hot magma. This means that water is native to the Moon.
The researchers looked into KREEP-rich rocks. KREEP is what comes in the last stages of crystallization, and the rocks rich in it contain more potassium, rare Earth Elements and phosphorous among other heat-producing elements. coauthor Andrew Steele explained that, "Since water is insoluble in the main silicates that crystallized, we believed that it should have concentrated in the KREEP,"
To determine water in the lunar interior, the scientists studied hydroxyl, which is a compound with an oxygen atom bound with hydrogen, the only mineral that bears water in the moon mineral apatite.
"It is gratifying to see this proof of the OH contents in lunar apatite. The concentrations are very low and, accordingly, they have been until recently nearly impossible to detect. We can now finally begin to consider the implications -- and the origin -- of water in the interior of the Moon." remarked lunar scientist, Bradley Joliff of Washington University in St. Louis.
The findings of this study are published online in the early edition of the Proceedings of the National Academy of Sciences on the week of June 14.
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