(ORDO NEWS) — After a six-year journey, the brave spacecraft called Hayabusa2 returned to Earth’s atmosphere in late 2020 and landed in the Australian outback.
When researchers from the Japanese space agency JAXA opened it, they found its valuable cargo sealed and intact: a handful that Hayabusa2 managed to scoop from the surface of a high-speed asteroid.
Now scientists have begun to announce the first results of the analysis of these unusual samples. What they found suggests that this asteroid is part of the same material that formed our Sun four and a half billion years ago.
“Previously, we had only a few of these rocks to study, and they were all meteorites that fell to Earth and were kept in museums for decades and centuries, which changed their composition,” said geochemist Nicolas Dofas, one of the three researchers at the University of Chicago, who worked with an international team of scientists led by Japan to analyze the fragments.
“To get pristine samples from space is incredible. These are witnesses from parts of the solar system that we haven’t explored yet.”
In 2018, Hayabusa2 landed on the moving asteroid Ryugu and collected particles on and below its surface. After spending a year and a half in orbit around the asteroid, it returned to Earth with a pressurized capsule containing about five grams of dust and rocks.
Scientists around the world have been eagerly awaiting a unique specimen that could help redefine our understanding of how planets evolve and how our solar system formed.
Scientists are especially excited that these particles would never have made it to Earth without the spacecraft’s protective barrier.
“Usually we study only those parts of asteroids that are large enough to hit Earth as meteorites,” says University of Chicago geochemist Andrew M. Davis, another member of the analysis team. “If you took this handful and threw it into the atmosphere, it would burn up. You would lose it, and with it a lot of evidence about the history of this asteroid.”
“We haven’t had a sample like this yet. It’s impressive.”
Davis, Daufas and University of Chicago colleague Reika Yokochi are part of a team assembled to help Japanese researchers analyze samples.
Each part of the contents of the capsule is subjected to careful study. Yokochi is part of a team that analyzes gases that have entered the capsule or samples. Daufas and Davis are studying the chemical and isotopic composition of grains to reveal their history.
The first round of these results, reported in Science on June 9, reveals the composition of Ryugu.
This rock is similar to a class of meteorites known as “Ivuna-type carbonaceous chondrites”. These rocks have a chemical composition similar to that which we record on the Sun and are believed to date back to the very beginning of the existence of the solar system, about four and a half billion years ago – before the formation of the Sun, Moon and Earth.
Then all that existed was a giant swirling cloud of gas. Scientists believe that much of this gas was sucked into the center and formed the star we know as the Sun. When the remnants of this gas expanded into a disk and cooled, they turned into rocks that still float around the solar system today; looks like Ryugu might be one of them.
According to scientists, traces of the fact that they were once saturated with water are visible on the fragments.
“You have to imagine a floating aggregate of ice and dust in space that turned into a giant ball of mud when the ice was melted by nuclear energy from the decay of radioactive elements that were present in the asteroid at the time of its formation,” said Daufas. But surprisingly, today the rock itself seems relatively dry.
Using radioisotope dating, they calculated that Ryugu was only altered by the circulation of water about five million years after the formation of the solar system.
These results are of particular interest to researchers as they hint at similar formation conditions for comets and some asteroids such as Ryugu.
“By studying these samples, we can determine the temperature and conditions that must have been during their lifetime and try to understand what happened,” Yokochi explained.
She likened the process to trying to figure out how the soup was made, but only with the end result, not with the recipe: “We can take the soup, separate the ingredients, and from their state try to determine how hot they were and in what order.”
The scientists noted that part of the find will be put on hold so that we can analyze it with better technology in the future, just as was done with the Apollo lunar samples.
After we received lunar samples from Apollo 50 years ago, our understanding of how the Moon formed has completely changed,” Davis said. We are still learning something new from them, because our instruments and technologies improved.”
“It will be the same with these samples. It’s a gift that keeps on giving.”
The mission is the first of several international missions that will bring back samples from another asteroid called Bennu, as well as unexplored regions on our Moon, Mars and the Martian moon Phobos. All this should happen in the next 10-20 years.
“This has received very little attention from the public and some decision makers, but we are entering a new era of planetary exploration that is unprecedented in history,” Daufas said. “Our children and grandchildren visiting museums will see returned fragments of asteroids, Mars and hopefully other planets.”
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