Cosmochemists have made the first-ever measurements of water contained in samples from the surface of an asteroid.

The team’s findings suggest that impacts early in Earth’s history by similar asteroids could have delivered as much as half of our planet’s ocean water.

«We found the samples we examined were enriched in water compared to the average for inner solar system objects,» says Ziliang Jin. A postdoctoral scholar in ASU’s School of Earth and Space Exploration, he is the lead author on the paper published May 1 in Science Advances reporting the results. His co-author is Maitrayee Bose, assistant professor in the School.

«It was a privilege that the Japanese space agency JAXA was willing to share five particles from Itokawa with a U.S. investigator,» Bose says. «It also reflects well on our School.»

The team’s idea of looking for water in the Itokawa samples came as a surprise for the Hayabusa project.

«Until we proposed it, no one thought to look for water,» says Bose. «I’m happy to report that our hunch paid off.»

In two of the five particles, the team identified the mineral pyroxene. In terrestrial samples, pyroxenes have water in their crystal structure. Bose and Jin suspected that the Itokawa particles might also have traces of water, but they wanted to know exactly how much. Itokawa has had a rough history involving heating, multiple impacts, shocks, and fragmentation. These would raise the temperature of the minerals and drive off water.

Story Source:
Materials provided by Arizona State University. Note: Content may be edited for style and length.