Scientists believe asteroids may have carried water to Earth

Researchers analyzed rare samples collected from a six-year Japanese space mission and their findings were published Monday in the science journal Nature.

The material was brought back to Earth in 2020 from the asteroid Ryugu. Scientists studied 0.2 ounces (5.4 grams) of rocks and dust gathered by a Japanese space probe. The Hayabusa2 probe landed on the asteroid to collect the sample from its surface.

"The Hayabusa2 spacecraft conducted two touchdowns and sample collections on Ryugu. The first touchdown on 21 February 2019 obtained surface material that was stored in Chamber A of the return capsule, and the second, on 11 July 2019, collected material close to an artificial crater formed by a small carry-on impactor," the journal states.

Ryugu particles are the most uncontaminated extraterrestrial materials studied so far, giving scientists the best available match to the bulk solar system composition.

Researchers eventually discovered organic matter in the Ryugu samples.

"Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth's water," reads the study.

But it also notes the delivery of water by an asteroid to Earth "is still a subject of notable debate."

The Hayabusa2 was launched in 2014, traveling more than 186 million miles to Ryugu. It returned to Earth's orbit two years ago to drop off a capsule containing the sample.