The mystery of the origin of water on Earth finally solved?

Our Earth is not the only one rocky planet of Solar system. But it still has a characteristic that others do not have: it is covered in water more than 70%! And researchers have long questioned its origin. Today a team led by the University of Glasgow (Scotland) argues that the solar wind, composed in particular of ions hydrogen, could have created, on the surface of tiny grains of dust, a water then deposited on Earth by asteroids which would have crossed the trajectory of our Planet at the beginning of the history of our Solar System.

Remember that one of the hypotheses to explain the presence of water on Earth involves collisions with asteroids of type C – carbonaceous asteroids, like 75% of asteroids – in the last phases of our planet’s formation. But the isotopic footprint of these objects does not quite match. Another source seems necessary.

Water for space missions

So the researchers turned to an S-type asteroid – asteroids mostly made up of silicates. And they conducted a thorough analysis of the few grams of dust in theItokawa asteroid brought back to Earth in 2010. Thanks to an atomic tomographic probe, which makes it possible to observe resolution the spatial distribution of atoms of a sample, scientists have indeed had access to the first 50 nanometers from the surface of these dust grains. They would contain the equivalent of 20 liters of water per cubic meter. Water isotopically lighter than that which could have arrived on Earth at back type C asteroids. The trail looks good.

The researchers also hope that their work will be useful to future space missions. Because they show that the same weathering process that created water on Itokawa probably occurred on planets devoid of atmosphere. So the astronauts might be able to collect fresh water directly from the dust on the surface of the Moon, for example.