The giant asteroid Ryugu had water

Large amounts of water will once have crossed the Asteroid Ryugu – an indication that asteroids may have brought much more water to Earth than it was thought so far.

The terrestrial remains involved in mystery. The hypothesis that asteroids have been one of its sources has already been placed, but doubts about whether sufficient impacts will have occurred to explain all the water that exists today on the planet.

The first images of suggested that the asteroid was very drier than expected, but more recent studies have revealed that the object is full of fractures that, in times, could have been filled with crucial ingredients for life – Including water.

Now, a new investigation indicates that this celestial body with about 800 meters may, at any given time, have had liquid water to circulate inside – and, even more surprisingly, much later in the history of the solar system of what was thought to be possible.

The conclusions, presented in a new one, published last week in the magazine Naturereinforce the theory that water asteroids may have been responsible for Bring the first reserves of H₂O to Earththousands of millions of years ago.

“This changes the way we think about the long -term destination of water in asteroids,” he said Tsuyoshi Iizukamain author of the study and associate professor at the Department of Earth and Planetary Sciences of the University of Tokyo, in a statement about the work. «The water remained for a long time and did not run out as quickly as thought».

When the sun was still young, it was surrounded by a so -called protoplanetary disk, consisting of material that would give rise to the planets. The remains of this process formed the asteroids.

Many of the type C asteroids, or carbonaceouslike Ryugu, they formed beyond or near a particular frontier known as the “ice line”, where temperatures were low enough for water to condense in tiny ice grains.

So far, astronomers have believed that the presence of liquid water would only have been possible in the most primordial moments of the solar system.

In the vacuum of space, the water, even protected inside asteroids, should evaporate or freeze over timeas the absence of atmospheric pressure drastically reduces its boiling point. It was thought that the little remaining water would be stuck in mineralsin molecular form.

But the new data suggest that this It may not always be like this.

The team analyzed microscopic samples of rock collected from the asteroid by the Hayabusa2 probe2 of the Japanese space agency Jaxa, between 2018 and 2019. In particular, they measured the Radioactive decay rate of the isotopes lutecio-176 and hafnio-176 to estimate the age of Ryugu-but the results were not right, although it is usually a reliable method of dating.

«We got ages around 4.8 billion years For samples of Ryugu, far superior to the age of the solar system, ”explained iizuka to. «This means that the“ clock ”is deregulated in Ryugu’s samples.”

E What could have deregulated this “clock”? According to the investigators, the presence of a liquid which will have dragged part of the isotopes of Lutecio.

This points to the existence of running water in Ryuguor in the original rock from which it was formed, about a thousand million years after its formation. As a result, this means that there must have been a considerable reserve of cold water that survived throughout this long period before melting.

The team It still doesn’t know for sure Which may have caused the defrost, as the heat of the sun should not penetrate sufficiently in the asteroid. They suspect that another object has collided with Ryugu, fragmenting it and warming it.

The implications are, in any case, impressive. This leaves an open one window of at least billion years During which rocky blocks full of ice could have collided with the earth and supplied water in substantial quantities – not just small amounts in the minerals.

This discovery It can change not only the way you think that the earth has acquired its oceans, but also the form how other worlds were formed.

“The idea that objects like Ryugu have been able to keep ice for so long is extraordinary,” said Iizuka. «This suggests that the building blocks of the earth They were much richer in water of what we imagined. »