Half the Earth’s oceans may have come from asteroids


Asteroids may have provided up to half of the Earth’s ocean water, new research shows.

Arizona State University recently found water in fragments of an asteroid known as Itokawa. This discovery suggests impacts from other asteroids during the early parts of Earth’s history may have sourced much of the water for the planet’s oceans.

Researchers published the findings Wednesday in the journal Science Advances.

“We found the samples we examined were enriched in water compared to the average for inner solar system objects,” Ziliang Jin, a researcher at Arizona State University and study lead author, said in a news release.

The samples were taken from an asteroid known as Itokawa during Japan’s Hayabusa space probe mission. Itokawa is approximately 1,800 feet long and between 700 and 1,000 feet wide.

ASU researchers got a hold of the samples and found they contained a mineral called pyroxene. Terrestrial samples analyzed by the researchers also had pyroxene. This similarity hints that water from other asteroids may have helped populate the Earth’s oceans.

“Until we proposed it, no one thought to look for water,” said Maitrayee Bose, a researcher at ASU and study co-author. “I’m happy to report that our hunch paid off.”

To further this research, NASA has scheduled a mission to collect samples from the asteroid Bennu in summer 2020 and bring them back to Earth by 2023.

“The Hayabusa mission to Itokawa has expanded our knowledge of the volatile contents of the bodies that helped from Earth,” Bose said. “It would not be surprising if a similar mechanism of water production is common for rocky exoplanets around other stars.”

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