Evidence of water movement found in meteorites that only recently fell to Earth

A team of researchers affiliated with institutions in Australia, the U.S. and France has found evidence of relatively recent water movement in meteorites that only recently collided with the Earth.

In their paper published in the journal Science, the group describes their study of carbonaceous chondrite (CC) meteorites that landed on the surface of the Earth within the past century and what they found.

Prior research has suggested that most, if not all, CC meteorites were formed approximately 4.5 billion years ago as part of larger asteroids. To find out if recent arrivals might have evidence of a water history, the researchers looked at uranium and thorium distributions in samples—the former is water-soluble while the latter is not.

Logic suggests that if water ever existed in the meteorite, it would have had to move as it melted, and that movement would be reflected in the distribution of thorium and uranium isotopes.

Also, both isotopes have short half-lives, which means if their distributions in meteorites could be found, they would have occurred relatively recently—on the order of a few million years.

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While studying nine of the carbonaceous chondrite (CC) meteorites, scientists found the pattern of thorium and uranium suggesting that water had flown on these meteorites due to melting of ice within the last one million years.