Chemical and isotopic analyses of samples returned by the Hayabusa2 mission from the asteroid Ryugu

The recent success of asteroid sample return missions has led to significant advances in Solar System science. JAXA's Hayabusa2 successfully retrieved and returned to Earth a total of 5.4 grams of samples from the C-type asteroid Ryugu. Sample return missions are critical to the scientific community, as they provide pristine, terrestrially unaltered extraterrestrial material. The analytical data obtained in laboratories for samples collected by space missions will facilitate the understanding of the formation and evolution of the Solar System. I was appointed deputy leader of the Initial Analysis Chemistry team of Hayabusa2 project, and was heavily involved in analyzing the chemical and isotopic compositions of Ryugu materials. A series of analyses of these samples indicated that the mineral, chemical, and isotopic compositions of Ryugu bear a strong resemblance to those of the Ivuna-type (CI) carbonaceous chondrites. CI chondrites have been recognized as a unique group of meteorites with a chemical composition similar to that of the solar photosphere except for highly volatile elements and Li. In the seminar, I will present the meaning and significance of the compositional similarity between Ryugu and CI chondrites. I will also present our recent activities in a new project called the Ryugu Reference Project, which was initiated to maximize the potential value of the returned samples.