(ORDO NEWS) — Mineral samples collected from the asteroid Ryugu by Japan‘s Hayabusa 2 spacecraft are helping scientists study the chemical composition of the early solar system.
Scientists found that the carbonate minerals of the asteroid were crystallized as a result of reactions with water. Water initially formed on the asteroid in the form of ice, and then warmed up to a liquid state.
The scientists say these carbonates formed very early – during the first 1.8 million years of the solar system’s existence – and they preserve data about the temperature and composition of the asteroid’s aqueous fluid as it existed at that time.
According to Kevin McKeegan, a professor at the University of California, Ryugu is the first carbonaceous asteroid from which samples have been collected and studied.
It had no potentially polluting contact with the Earth. By analyzing the samples, scientists can get an idea not only of how Ryugu formed, but also where.
“The Ryugu samples tell us that the asteroid and similar objects formed relatively quickly in the outer solar system, behind condensation fronts of water and carbon dioxide ices, probably as small bodies,” McKeegan said.
According to the study, the Ryugu carbonates formed several million years earlier than previously thought.
They indicate that Ryugu or the parent asteroid it may have broken off from formed as a relatively small object, probably less than 20 kilometers in diameter.
And while Ryugu is currently only about 1 kilometer in diameter, it is highly unlikely that it was ever a large asteroid.
The researchers noted that any larger asteroid formed in the early solar system would have been heated to high temperatures by the decay of large amounts of aluminum-26.
This would have resulted in the melting of rocks throughout the interior of the asteroid, along with chemical differentiation such as separation of metal and silicate.
However, there is no evidence of these processes on Ryugu.
The asteroid’s chemical and mineralogical compositions are equivalent to those found in chemically primitive CI chondrites, which are also believed to have formed in the outer solar system.
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