Japan determines when Ryugu asteroid’s parent body formed
A research group from Hokkaido University and other institutions in Japan has established that the parent celestial body of the asteroid Ryugu formed within 2 million years after the beginning of the Solar System’s formation about 4.6 billion years ago. The results were published in the U.S. scientific journal Science, The Japan Times reports.
Analysis of samples from Ryugu
Scientists studied minerals in sand samples collected from the asteroid by Japan’s Hayabusa2 spacecraft. The probe delivered these samples to Earth in 2020.
The samples contain minerals and organic matter formed as a result of reactions between rock and water. The water appeared after ice melted, as the temperature inside the parent body gradually rose due to heat released by radioactive materials.
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Dolomite as an age indicator
Associate Professor Noriyuki Kawasaki of Hokkaido University and his colleagues determined the age of dolomite, a carbonate mineral from the Ryugu samples, using radioisotopes. To improve accuracy, they applied a new method for correcting errors and reconstructed temperature changes inside the parent body through computer modeling.
The analysis showed that dolomite formed about 4.56 billion years ago at a temperature of around 90 degrees Celsius. Taking into account the time needed to heat up to this level, the team concluded that Ryugu’s parent body formed within 2 million years of the beginning of the Solar System’s formation.
