Oxygen isotope evidence from Ryugu samples for early water delivery to Earth by CI chondrites

• Published in: Nature astronomy Vol. 7; no. 1; pp. 29 - 38
• Main Authors: Greenwood, Richard C., Franchi, Ian A., Findlay, Ross, Malley, James A., Ito, Motoo, Yamaguchi, Akira, Kimura, Makoto, Tomioka, Naotaka, Uesugi, Masayuki, Imae, Naoya, Shirai, Naoki, Ohigashi, Takuji, Liu, Ming-Chang, McCain, Kaitlyn A., Matsuda, Nozomi, McKeegan, Kevin D., Uesugi, Kentaro, Nakato, Aiko, Yogata, Kasumi, Yuzawa, Hayato, Kodama, Yu, Tsuchiyama, Akira, Yasutake, Masahiro, Hirahara, Kaori, Tekeuchi, Akihisa, Sekimoto, Shun, Sakurai, Ikuya, Okada, Ikuo, Karouji, Yuzuru, Nakazawa, Satoru, Okada, Tatsuaki, Saiki, Takanao, Tanaka, Satoshi, Terui, Fuyuto, Yoshikawa, Makoto, Miyazaki, Akiko, Nishimura, Masahiro, Yada, Toru, Abe, Masanao, Usui, Tomohiro, Watanabe, Sei-ichiro, Tsuda, Yuichi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01.01.2023
• Subjects: Asteroids; Earth; Isotopes; Meteors & meteorites; Oxygen isotopes; Porosity; Spacecraft; Water delivery
• ISSN: 2397-3366; 2397-3366
• DOI: 10.1038/s41550-022-01824-7

Abstract The delivery of water to the inner Solar System, including Earth, is still a debated topic. A preferential role for hydrated asteroids in this process is supported by isotopic measurements. Carbonaceous chondrite (CC) meteorites represent our main source of information about these volatile-rich asteroids. However, the destruction of weaker materials during atmospheric entry creates a bias in our CC data. The return of surface materials from the C-type asteroid 162173 Ryugu by the Hayabusa2 spacecraft provides a unique opportunity to study high-porosity, low-density, primitive materials, unrepresented in the meteorite record. We measured the bulk oxygen isotope composition from four Ryugu particles and show that they most closely resemble the rare CI (CC Ivuna-type) chondrites, but with some differences that we attribute to the terrestrial contamination of the CI meteorites. We suggest that CI-related material is widespread among carbonaceous asteroids and a more important source of Earth’s water and other volatiles than its limited presence in our meteoritic collection indicates.