Dust motes that a Japanese space probe recovered from an asteroid some 300 kilometers from Earth have revealed a surprising component: a drop of water.
The discovery offers new support for the theory that life on Earth may have been seeded from outer space.
The findings are in the latest research to be published from the analysis of 5.4 grams of stones and dust that the Hayabusa-2 probe collected from the asteroid Ryugu.
“This drop of water has great significance,” lead scientist Tomoki Nakamura of Tohoku University told reporters ahead of the research’s publication in the journal Science on Friday.
“Many researchers believe that the water was brought [from outer space]but we actually discovered water on Ryugu, an asteroid near Earth, 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 prized cargo has already yielded several insights, including organic material that showed that some of the building blocks of life on Earth, amino acids, may have formed in space.
The team’s latest discovery was a drop of fluid in the Ryugu sample “which was carbonated water containing salt and organic matter,” Nakamura said.
That bolsters the theory that asteroids like Ryugu, or its larger parent asteroid, could have “provided water, which contains salt and organic matter” in collisions with Earth, he said.
“We have uncovered evidence that this may have been directly related to, for example, the origin of the oceans or organic matter on Earth.”
Nakamura’s team, which is made up of about 150 researchers, including 30 from the US, Britain, France, Italy and China, is one of the largest teams to analyze the Ryugu sample.
The sample has been divided among different scientific teams to maximize the possibility of new discoveries.
Kensei Kobayashi, an astrobiology expert and professor emeritus at Yokohama National University who is not part of the research group, made the discovery.
“The fact that water has been discovered in the sample itself is surprising,” given its fragility and the chances of it being destroyed in outer space, he said.
“It suggests that the asteroid contained water, in the form of fluid and not just ice, and that organic matter may have been generated in that water.”