Dust grains recovered by a Japanese space probe from an asteroid some 300 million kilometers from Earth have revealed a surprising component: a drop of water, scientists said Friday.
The discovery offers new support for the theory that life on Earth was seeded from outer space. The results are part of the latest research published from the analysis of 5.4 grams of rock and dust collected by the Hayabusa-2 probe from the asteroid Ryugu.
“This drop of water has great significance,” senior scientist Tohoku University’s Tomoki Nakamura told reporters ahead of the research’s publication in the journal Science on Friday.
“Many researchers think the water was brought in (from space), but we actually discovered water in Ryugu, a near-Earth asteroid, for the first time. »
Hayabusa-2 launched in 2014 on its mission to Ryugu and returned to Earth orbit two years ago to drop off a capsule containing the sample.
The precious cargo has already yielded several pieces of information, including organic matter which has shown that some of the building blocks of life on Earth, amino acids, may have been formed in space.
Research published on Friday indicates that the team found a drop of liquid in Ryugu’s sample “which was carbonated water containing salt and organic matter”, Nakamura said.
This supports the theory that asteroids like Ryugu, or its larger parent asteroid, could have “provided water, which contains salt and organic matter” during collisions with Earth, Nakamura said.
“We found evidence that this (process) may have been directly linked to, for example, the origin of the oceans or organic matter on Earth. »
Nakamura’s team, made up of around 150 researchers – including 30 from the United States, Britain, France, Italy and China – is one of the largest teams analyzing the Ryugu sample.
The sample was divided between different scientific teams in order to maximize the chances of new discoveries.
Kensei Kobayashi, an expert in astrobiology and professor emeritus at Yokohama National University who is not part of the research group, welcomed the discovery.
“The fact that water was discovered in the sample itself is surprising,” given its fragility and the risks of it being destroyed in space, he told AFP. .
“This suggests the asteroid contained water – in the form Water in asteroid dust offers clues to life on Earth
liquid and not just ice — and organic matter may have been generated in this water. »