Our view of the moon as a barren monochromatic wasteland is rapidly changing. It wasn’t more than two years ago that NASA’s LCROSS satellite smashed into the moon kicking up over 120 litres of water ice, validating the belief that lunar water did exist. But a new study has confirmed that water has been a part of the moon since the beginning.
These studies looked at moon rocks brought back during the Apollo 15 and 17 missions. The initial experiments carried out in 2008 by Alberto Saal at Brown University showed that water had been trapped in volcanic glass beads. A new study carried out by Erik Hauri at the Carnegie Institution looked at different moon rocks; moon-magma trapped inside crystals. Scientists believe that these moon rocks were formed billions of years ago during the moon’s volcanic stage. In these, the water in the magma was protected by the cooling rock instead of boiling away into space, trapping it in what are called “melt inclusions.”
Hauri’s work not only confrimed Saal’s findings, but found it in such concentrations that scientists might have to re-think their theories about the how the moon came to be.
Analysis of these melt inclusions has found water in quantities around 615 to 1410 parts per million. This is comparable to the water content of the Earth’s fiery mantle, which has a water concentration about 500 to 1000 parts per million. And while this doesn’t mean that we’ll have swimming pools on the moon anytime soon, it does call into question our understanding of how the moon formed in the first place.
The most widely accepted theory of how the moon came to be hinges on a freshly minted and still cooling Earth being smacked by a larger object about the size of Mars. In the midst of the cataclysm, a hunk of the Earth was spun off and became our moon. This theory explains the moon’s low density, since most heavier elements would have already settled in the Earth’s core. It also explains the moon’s lack of certain delicate materials that would not have survived being spun off so violently. Water was thought to be one such element, but Saal’s work and the recent confirmation call at least that portion of the theory into question.
More samples and more analysis are obviously needed to help fill in the gaps of the moon’s birth, but it is nothing short of amazing how our view of the moon has changed in less than five years. Who knows what we’ll be thinking of our orbiting neighbor in five more!
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