Nearly two years after Japan’s Hayabusa2 mission returned to Earth, samples from the asteroid Ryugu continue to provide valuable insight into the history of the early Solar System. Research by scientists from the Institut de Physique du Globe de Paris, Université Paris Cité and CNRS1 as part of an international consortium reveals the zinc and copper isotopic composition of the asteroid Ryugu. Isotopic signatures indicate that the composition of Ryugu is close to Yvuna-like carbonaceous chondrites, and Ryugu-like material from the outer Solar System is ∼5-6% of the Earth’s mass. These results were published in the journal December 12, 2022. Nature Astronomy.

Meteorites found on Earth give scientists access to samples representing the earliest moments of the Solar System’s existence. However, the December 2020 return to Earth of the Japanese space agency JAXA-led Hayabusa2 mission, which brought a 5 gram fragment from the asteroid Ryugu, takes a big step forward and offers the opportunity to analyze unaltered samples. by their coming and their staying on Earth.

Initial analyzes by an international team, including researchers from the World Institute of Physical Research in Paris, the City University of Paris and the CNRS, showed that the composition of the Ryugu asteroid is close to that of carbonaceous chondrites. Yvuna type (CI) – the most chemically primitive meteorites, which by their composition are considered closest to the sun. However, some isotopic signatures (for example, titanium and chromium) overlap with other carbonaceous chondrite groups, so the details of the relationship between Ryugu and CI chondrites are not yet fully understood.

Zinc and copper are two moderately volatile elements and are essential for studying volatile accumulation processes during tellurium planet formation. Different carbonaceous chondrite groups show different isotopic compositions of zinc and copper, while CI chondrites are richer in volatile elements. The scientists performed additional analyzes of Ryugu’s zinc and copper isotopic composition, giving them access to an important tool for studying the asteroid’s origin.

In a study published on December 12, 2022 in the journal Nature Astronomy An international team led by IPGP cosmochemists Marine Paquet and Frédéric Moignier showed that the copper and zinc isotopic ratios in samples from Ryugu were the same as for CI. chondrites, but different from all other types of meteorites.

Conclusively confirming the similarity between Ryugu and CI chondrites, this study reveals that these primitive samples from Ryugu represent the best solar composition estimate to date for copper and zinc. Finally, Ryugu’s zinc isotopic composition can also be used to study the history of the accumulation of moderately volatile elements on Earth, which is important for the development of planetary habitability. The study also shows that Ryugu-like material makes up about 5% of Earth’s mass.