The dust particles found by a Japanese spacecraft on an asteroid about 300 million kilometers from Earth contain a surprising component: a drop of water. That 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 following the 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,” said Tohoku University’s chief scientist, Tomoki Nakamura. “Many researchers already believed that water was brought from space, but we have actually discovered water for the first time in a near-Earth asteroid.”

    Hayabusa-2 was launched in 2014 on its mission to Ryugu, and returned to orbit two years ago to deposit a capsule containing the monster. The precious cargo has already provided several insights, including organic material showing that some building blocks of life on Earth, amino acids, may have formed in space.

    Asteroid Ryugu. © AFP

    The team’s latest discovery was a drop of liquid in the Ryugu sample. “The drop is carbonated water with salt and organic matter,” said Nakamura. “That reinforces the theory that asteroids like Ryugu, or larger asteroid, have supplied water with organic matter to Earth,” he said. “So we have discovered evidence that this could be directly related to, for example, the formation 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 the largest team to analyze Ryugu’s sample. The sample is divided among several scientific teams to maximize the chance of new discoveries.

    Kensei Kobayashi, an astrobiology expert at Yokohama National University who is not part of the research group, applauded 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 asteroids can contain water, in the form of liquid and not just in the form of ice. This allows organic material to be moved through space.”