Speaker
Description
Sample return missions are of vital importance to the scientific community, particularly in the domains of planetary science and cosmochemistry. These missions provide pristine, terrestrially unaltered extraterrestrial materials that can be analyzed in a laboratory with a level of detail that is not possible through remote sensing. The recent success of asteroid sample return missions has led to significant advancements in solar system science. The Hayabusa2 mission by JAXA successfully retrieved a total of 5.4 grams of samples from two locations on the surface of the C-type asteroid (162173) Ryugu and returned them back to Earth. A series of analyses for the elemental abundances of these samples indicated that Ryugu bear a strong resemblance to those of the Ivuna-type (CI) carbonaceous chondrites, which are a unique group of meteorites with a chemical composition similar to that of the solar photosphere except for highly volatile elements (noble gases, H, C, N, and O) and Li that was destroyed in the Sun by nuclear reactions. Additionally, the isotopic compositions in bulk Ryugu samples were generally consistent with those of CI chondrites, suggesting that the source materials of Ryugu and CIs share a common genetic heritage. Since the materials observed in CI chondrites may have been modified on Earth, the Ryugu samples are more chemically pristine than other Solar System materials that have been analyzed in laboratories, including CI chondrites. Thus, it is suggested that Ryugu is the most primordial material in the Solar System and serves as a crucial reference for studying the origin and evolution of the Solar System.
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