Asteroids are many things: dinosaur killers, archives from the early days of the solar system, Planet defense goals – But they shouldn’t be an aquatic world. Good?
Well, at least not today. But in the early days of the formation of the solar system, Ryugu – the diamond-shaped target of the Japan Aerospace Exploration Agency (JAXA). Hayabusa 2 Important: it has a small circle inside it.
Before the asteroid existed today, high-resolution isotope analysis showed it was part of an increasingly elderly parent before exploding in a collision. But what’s even more surprising is that within this tiny ocean, some of the dry silicates from the original asteroid have managed to remain unchanged. New article from one of Hayabusa’s organizational team Posted this month in natural astronomy They got what they showed about the composition of Ryugu’s father and the asteroids in the early solar system.
What’s new – In December 2020, Hayabusa2 returned more than five grams of Ryugu after a six-year mission. Since the sample is a relatively small number of small grains, each is marked with its own name and number. In this case, the team’s analysis relied on just one of these particles, C0009.
talk with backwardsworld of cosmic chemical isotopes Ming Chang Liu of UCLA found that C0009 was particularly interesting because “it is distinguished by the content of small amounts of anhydrous silicates”, meaning it contains oxygen-rich minerals that are unaffected by the water in the center of the sample which is heavily altered by H2O.
Ryugu’s composition was greatly altered by the liquid water within him. Despite having formed in the cold depths of the outer solar system, water and carbon dioxide have accumulated together in the protolith which is Ryugu’s parent along with short-lived radioactive isotopes. As radioactive rocks heat the ice around them, Liu notes, they “will begin to float within the parent body” and over time will convert the silicates and pyroxenes that formed Ryugu’s predecessors into water-carrying silicates.
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Therefore, the remaining anhydrous silicates give the team an idea of what other materials looked like in the early Solar System before they collided with the tiny Ryugu ocean. The material appears to be the oldest material formed in the solar photosphere. The oxygen isotopes in the samples the team worked on showed that the asteroid contained amoebic olivine and magnesium-rich chondrites fused directly from the solar nebula.
Moto Ito, a cosmic chemist at the Japanese Agency for Marine Geosciences Technology and a member of the larger Phase II team, is the lead author, along with Liu and others, of Original Ryugu Particle Studyshowing how CI meteorites on Earth have changed due to our more volatile environment.
talk with backwardsIto observes that, while knowing the chemical composition “it does not tell us where the parent body was formed”, however “it allows us to establish a sort of history of Ryugu and how it was formed in the outer solar system”.
because matter – This work comes from the efforts of the larger Phase Two organizational team. After the Hayabusa2 crossed the ground to unload its payload, the five grams of samples it was carrying were divided into eight teams: six of which performed specific preliminary analyzes – for chemical composition, rocky and sandy materials, volatile organic , solid and soluble – on materials, and two large international teams, others They are working to clarify the potential scientific impact of the samples.
In June, Liu and Ito’s senior team from Okayama University in western Japan released their interpretation of the sample. They found that Ryugu phyllosilicates are similar to CI chondrites, a rare and very primitive type of meteorite that is mainly collected in Antarctica.
But since “they may have been there for decades, years and centuries before we collected them,” Liu notes, “the Earth has a very reactive atmosphere, so the CI chondrites will interact with the atmosphere.” By comparison, the Hayabusa2 samples “are probably the purest chondrite material ever.”
The survival of these elements from the Ryugu Protolith is perhaps even more surprising given the work of some of the other teams. stone analysis group They released their preliminary results this month Science, which included Ryugu’s liquid water which was confined within the crystal. Since Ryugu collects frozen carbon dioxide and water ice as it forms, the liquid water in the sample is carbonated.
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What’s next – in some context Ryugu is already on his way to Earth. Last May, NASA Osiris Rex The spacecraft left the asteroid Bennu after shoveling perhaps half a kilo of rock to begin its journey back to Earth. This is after OSIRIS-REx It unexpectedly created a 20-foot-wide hole on Bennu’s side The result was that he joined with far less force than anyone expected.
Like Ryugu, Bennu is a relatively native carbon asteroid, albeit of a different type: B-type asteroids like Bennu appear slightly bluer than Ryugu and other C-type asteroids, which appear red. But regardless of color, according to cosmologist Ito, finding similar complex carbon components in the sample “would tell us about the distribution of organic components in the solar system.”
While answering questions about Ryugu’s makeup, this work also raises questions about how Ryugu fits into more primitive patterns of asteroids and meteorites. According to Liu, the team believes that despite the distinct classes that emerged to encompass all of the different chondrites found on Earth over the years, “the starting materials were probably very similar.” “We just wanted to be a little provocative, move the plate a little bit and try to change the paradigm,” she added.