Our planet is covered in water: 超过 70 per cent of its surface made up of oceans, it is far more water-rich than other planets in our solar system. But scientists have long struggled to know where all of that has come from.
Now a new study has suggested that surprising possibility that it came to Earth from the Sun.
“An existing theory is that water was carried to Earth in the final stages of its formation on C-type asteroids, however previous testing of the isotopic ‘fingerprint’ of these asteroids found they, on average, didn’t match with the water found on Earth meaning there was at least one other unaccounted for source,” Phil Bland, a professor at Curtin University and one of the scientists involved in the study, said in a statement.
“Our research suggests the solar wind created water on the surface of tiny dust grains and this isotopically lighter water likely provided the remainder of the Earth’s water.
“This new solar wind theory is based on meticulous atom-by-atom analysis of miniscule fragments of an S-type near-Earth asteroid known as Itokawa, samples of which were collected by the Japanese space probe Hayabusa and returned to Earth in 2010.
“Our world-class atom probe tomography system here at Curtin University allowed us to take an incredibly detailed look inside the first 50 nanometres or so of the surface of Itokawa dust grains, which we found contained enough water that, if scaled up, would amount to about 20 litres for every cubic metre of rock.”
The research could not only prove useful in telling the story of our Earth, but helping us leave it, 科学家说. We might be able to use the same technique in future space missions.
“How astronauts would get sufficient water, without carrying supplies, is one of the barriers of future space exploration,” said Luke Daly, another scientist who worked on the paper.
“Our research shows that the same space weathering process which created water on Itokawa likely occurred on other airless planets, meaning astronauts may be able to process fresh supplies of water straight from the dust on a planet’s surface, such as the Moon.”
A paper describing the findings, ‘Solar wind Contributions to the Earth’s Oceans’, is published in Nature Astronomy.