Archive for January 8, 2015

Moon Water Differs from Earth Water

The Apollo moon missions ended almost 40 years ago. But for lunar scientists, they’re gifts that keep on giving. Researchers studying rocks brought back by astronauts have found that the moon’s scarce water has a different chemical signature than Earth water. Which leads to the conclusion that the water probably came from comets. The study appears in the journal Nature Geoscience. [James Greenwood et al., “Hydrogen isotope ratios in lunar rocks indicate delivery of cometary water to the Moon“]
Earth and the moon in a Nasa composite imageThe researchers used what’s called an ion microscope to compare the amount of normal hydrogen in the moon rocks to the amount of the hydrogen isotope deuterium, which carries an extra neutron. They found deuterium at higher levels than it’s found in Earth water—but at levels similar to the comets Hale-Bopp, Hyakutake and Halley. Which suggests comets deposited water on the ancient moon, shortly after its formation four-and-a-half billion years ago.

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