Asteroids are many things — dinosaur killers, archives of the early days of the solar system, planetary defense targets — but they shouldn’t be watery worlds. the correct?
Well, at least not these days. But in the early days of the formation of the solar system, Ryugu was the diamond-shaped target of the Japan Aerospace Exploration Agency (JAXA). Hayabusa 2 Mission – There was a small sea inside.
Before the asteroid was today, high-resolution isotope analysis shows it was part of a much older, older father before it exploded in a collision. But what is even more surprising is that within this small ocean, some dry silicates from the original asteroid have managed to remain intact. A new paper from Hayabusa’s organizing team was published this month in natural astronomy A take on Ryuku’s parents’ makeup and what they show about asteroids in the early solar system.
what’s new – In December 2020, Hayabusa2 returned five grams from Ryuku after a six-year journey. Since the samples are a relatively small number of small grains, each is marked with its name and number. In this case, the team’s analysis is based on one of these particles, C0009.
talking with reflectIsotope chemist Ming-Zhang Liu UCLA explains that C0009 is particularly interesting because it “distinguishes itself by the presence of a small amount of anhydrous silicates”—that is, it contains water-unaffected, oxygen-rich minerals in the middle of a sample strongly altered by H2O.
Ryoko’s makeup has been greatly altered due to the liquid water inside him. Although it formed in the cold depths of the outer solar system, water and carbon dioxide combined with ice formed Ryoko’s father and produced short-lived radioactive isotopes. As those radioactive rocks heat the ice around them, Liu notes, “they begin to float in the mother body”—and over time convert the silicates and pyroxenes that make up the Ryukyu precursor into water-bearing silicates.
The remaining anhydrous silicates give the team an idea of what other materials in the early Solar System looked like before they collided with Ryoko’s small ocean. The material looks like the oldest material that formed in the sun’s photosphere. Oxygen isotopes in the team’s sample showed that the asteroid contained amoebic peridot and magnesium-rich chondrites that were linked directly from the solar nebula.
Moto Ito, a cosmic chemist at the Japan Agency for Marine Geosciences Technology and a member of the broader Phase II team, was the lead author along with Liu and others. Studying the Ancient Ryukyu Particles This shows the ways in which CI meteorites on Earth have changed due to our more turbulent environment.
talking with reflectAlthough knowing the chemical composition “doesn’t tell us where the parent body originated from,” notes Ito, it “allows us to create a kind of Ryoko history, and how it formed in the outer solar system.”
Why is it important – This work stems from the larger Phase II organizing team effort. After Hayabusa2 dropped its payload and passed the Earth, the five-gram samples it brought were divided into eight groups: six specific primary analyzes—chemical composition, rocky and sandy materials, volatiles, solid and soluble organics—substances, and two large global work to clarify the scientific impact. potential for models.
In June, Liu and Ito’s larger team, based at Okayama University in western Japan, published a description of the models. They found that Ryoko phyllosilicates are similar to those of Ci chondrites, a rare and very ancient meteorite collected mostly in Antarctica.
But they “may have been sitting there for decades, years, and years before we caught them,” notes Liu, adding, “Earth has a very reactive atmosphere, so CI chondrites will interact with the atmosphere.” By comparison, samples from Hayabusa2 are probably the most beautiful chondrite material that can be obtained.
The survival of these elements from the Ryugu protolith may be even more surprising in light of the work of some other groups. The Stone Analysis Group released its preliminary results this month Science, which consists of liquid water from Ryoko confined within a crystal. Because Ryugu took frozen carbon dioxide and water during ice formation, the liquid water in the sample was carbonated.
What’s next – some Ryugu context is already on its way to Earth. Last May, NASA’s OSIRIS-REx spacecraft left the asteroid Bennu after shoveling half a pound of rock to begin its journey back to Earth. That’s after OSIRIS-REx unexpectedly made a 20-foot-wide crater in Bennu’s side – the result of sticking together to a much smaller degree than anyone expected.
Like Ryugu, Bennu is a relatively old carbon asteroid, although it’s a different type: B-type asteroids like Bennu appear bluer than Ryugu and their C-type counterparts. But regardless of color, according to cosmologist Ito, finding carbonate elements A similarly complex sample “will inform us of the distribution of organic elements in the solar system.”
While it answers questions about Ryuku’s makeup, the work also raises questions about how Ryuku fits into the scheme of older asteroids and meteorites. According to Liu, the team believes that “those starting materials can be very similar,” although the diversity has arisen over the years to include all the different chondrites found on Earth. “We want to be a little provocative, move the pot a little bit, and try to change the paradigm,” he added.