The latest evidence shows that it turns out that charged particles within the solar wind turn into water when they encounter space dust! Understanding this process is important for exploring the origin of water on Earth as well as for future human space exploration.
A diagram of the Earth under the influence of the solar wind
Many previous studies of meteorites have found that they carry large amounts of water, so scientists believe that the first water resources on Earth were probably brought by meteorites that fell to Earth. However, there is another problem with this theory that cannot be explained – the composition of water in meteorites is slightly different from the composition of water on Earth.
The proportion of heavy water in the water in alien meteorites is higher than that on Earth. Heavy water is a compound composed of deuterium, an isotope of hydrogen, and oxygen, with a somewhat larger mass than normal water composed of hydrogen and oxygen, hence the name heavy water. This suggests that there should be other sources of water on Earth.
Luke Daly of the University of Glasgow (UK) and colleagues think they may have found the answer. They were studying samples from the armature (Itokawa) asteroid collected by Japan’s Hayabusa probe in 2010, when they unexpectedly discovered that the original space dust is subject to radiation from the solar wind, will turn into water, and the amount of water that can be produced is not small.
Daley said, “For every cubic meter of asteroid material, you can get 20 liters of water.”
The solar wind is a stream of electrically charged particles blown by the sun and contains large amounts of hydrogen ions. This study found that these hydrogen ions combine to produce water when they encounter oxygen atoms inside the rocks on the asteroids.
The researchers speculate that the large amount of dust contained in the solar system at the beginning of its existence was blown by the solar wind to produce water, which was “sprayed” onto the Earth. And this water contains less deuterium isotopes.
Daley said, “The combination of these two water resources gave rise to the oceans on Earth today.” The researchers’ calculations show that if water from dust radiation and water from meteorites are mixed in a 50:50 ratio, the resulting water has the same ratio of deuterium and hydrogen isotopes as water on Earth. That is, the researchers believe that at least half of the water on Earth comes from the interaction of the solar wind and dust.
In addition to being able to answer questions about water resources from previous studies, Daley said the finding is also important for the future of human space exploration. “The surface dust of any space rock is radiated by the solar wind, and if humans were to establish a long-term base in outer space, they could consider using the dust to create water resources.”
The study was published Nov. 29 in the journal Nature Astronomy.