Lunar samples obtained during the Apollo missions recently revealed the presence of hydrogen: the H of H2O. Crystal and glass bead samples contained within moon rocks discovered during the Apollo 15 and 17 missions were studied for further information.
The study’s findings hinge on the hydrogen isotope
deuterium. Deuterium, unlike regular hydrogen, contains both a proton and a neutron. A deuterium/hydrogen ratio (D/H) is present at different levels in the water of meteorites, comets, and Earth. The study, lead by Alberto Saal of Brown University, found that the D/H ratio extrapolated from the crystal and bead samples was very similar to the D/H ratio of Earth water. Both were found to be similar to the D/H ratio of carbonaceous chondrites, as well.
“With a good degree of certainty, we know that the water came to the moon and Earth from primitive meteorites now located in the outer parts of the asteroidal belt,” said Saal. The asteroid belt is located between the orbits of Mars and Jupiter.
So why did the water not evaporate from the heat of the moon’s origins? Saal thinks the theory of a hot gas envelope, promoted by Caltech astrophysicist David Stevenson and others, could explain how the water remained protected throughout the fiery devastation. Even so, the idea does not account for the amount of water the moon currently retains.
“Although the moon has maybe five to 10 times less water than the Earth, that’s still a significant amount of water it retained. That’s a problem I don’t think we know the answer to yet,” he said in an interview with Space.com.
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