An Asteroid’s Water May Offer Clues to the Origin of Life on Earth

Itokawa is surprisingly wet

The samples came from the feature called the Muses Sea, which is the smooth area in the middle of Itokawa. Photo: Japan Aerospace Exploration Agency (JAXA)

By Neel V. Patel

Nine years ago, the Japan Aerospace Exploration Agency (JAXA) made history when its Hayabusa probe successfully brought samples of the asteroid Itokawa back to Earth. It was the first time we had ever gone to an asteroid, collects samples off the surface, and brought them back in pristine condition for study.

Now, according to findings recently published in the journal Science Advances, those samples have made history once again: they contain water.

“No one really expected to find even traces of water in the Itokawa grains,” says Maitrayee Bose, a cosmochemist at Arizona State University. It’s well-known that Itokawa (or rather, the parent body it descended from) had been torched to up to 1,500 degrees Fahrenheit, and perhaps higher when impacted by other rocks strewing around through space. There wasn’t much hope any water would be still preserved after such extreme conditions. “Before we embarked on this work, our back of the envelope calculations showed that it is indeed possible for the Itokawa grains to retain the original water in the right proportion from when the asteroid formed,” Bose says. “This is the first time someone has ever measured water in this asteroid.”