We know 71% of the Earth’s surface is covered by water — in fact, it’s the reason why the Earth is called the “blue planet.” This “elixir of life” also exists in the air as vapor, and in the ground as moisture. Water constitutes 60% of our bodies too. But where did it come from?
A new study offers answers: it may have been the solar winds that could have delivered water on the Earth’s surface.
“[S]cientists had long puzzled over the exact source of it all…” Philip Bland, a professor at the School of Earth and Planetary Sciences at Curtin University in Australia, said in a statement. “An existing theory is that water was carried to Earth in the final stages of its formation on C-type asteroids.” In other words, it was believed incoming asteroids full of water, were the source of origin.
Bland co-authored a study investigating how water made its way to the Earth, which was published in Nature Astronomyyesterday. This research suggests that contrary to past belief, asteroids may not be the source of water on Earth. “…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,” Bland said, explaining the composition of water from these bodies didn’t quite match the ones found on Earth.
Instead, the research points to the “surprising possibility” of water making its way to our planet from the Sun.
“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,” Bland noted.
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This is what the researchers believe happened: our solar system was full of dust in the early phases; water covering specks of dust that were floating around in the protoplanetary disk — or a rotating “disc of dense gas and dust” surrounding a newly-formed star — made their way to different planets and asteroids as they began forming.
The researchers based their findings on a detailed analysis of “S-type” asteroids whose samples were collected over a decade ago by the Japanese space probe Hayabusa. The solar wind consists largely of hydrogen ions that the sun emits, which combine with oxygen atoms in the asteroid rock to produce water (H20).
Ashley King at the Natural History Museum in London calls this finding quite “awesome.” “This is real evidence that it’s happening,” he told New Scientist, explaining that while scientists have believed in the occurrence of this process, they had little conclusive evidence to support it.
Besides taking us closer to solving what is possibly one of the biggest mysteries of the universe, the findings have interesting implications on the future of space exploration too. “How astronauts would get sufficient water, without carrying supplies, is one of the barriers of future space exploration,” Luke Daly from the School of Geographical and Earth Sciences at the University of Glasgow in the U.K., who was also the lead author of the study, pointed out.
With the present research, we may be closer to breaking this “barrier.”
“Every rocky surface will have small grains that have been irradiated by solar wind…If we want to put up permanent human habitation facilities on other worlds, you could look at the [dust] as a way of producing water,” Daly said. Eventually, it may be possible for astronauts to “process fresh supplies of water straight from the dust on a planet’s surface.”
