Dust particles picked up by a Japanese spacecraft from an asteroid about 300 meters from Earth have revealed a surprising component: a drop of water.
The discovery provides new support for the theory that life on Earth may have been seeded from space.
The findings are in the latest study published based on analysis of 5.4 grams of rocks and dust collected by the Hayabusa-2 probe from the asteroid Ryugu.
“This drop of water has great significance,” the chief scientist, Tomoki Nakamura of Tohoku University, told reporters before publishing the study in the journal Science on Friday.
“Many researchers believe that water was brought [from outer space]but we discovered water for the first time in Ryugu, a near-Earth asteroid.”
Hayabusa-2 was launched in 2014 during its mission to Ryugu and returned to Earth orbit two years ago to release a capsule containing the monster.
The precious cargo has already provided several insights, including organic material showing 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 liquid in the Ryugu sample “which was carbonated water containing salt and organic matter,” Nakamura said.
That supports the theory that asteroids like Ryugu, or its larger parent asteroid, when colliding with Earth “could have provided water containing salt and organic matter,” he said.
“We found evidence that this may be directly related to, for example, the origin of the oceans or organic matter on Earth.”
Nakamura’s team, made up of about 150 researchers — including 30 from the US, Britain, France, Italy and China — is one of the largest teams analyzing Ryugu’s sample.
The sample is divided among several scientific teams to maximize the chance of new discoveries.
Kensei Kobayashi, an astrobiology expert and professor emeritus at Yokohama National University who is not part of the research group, praised the discovery.
“The fact that water has been discovered in the sample itself is surprising,” given its fragility and the likelihood of it being destroyed in space, he said.
“It suggests that the asteroid contained water, in the form of liquid and not just ice, and that organic matter may have formed in that water.”