A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Motoo Ito ,Naotaka Tomioka ,Yuto Takei ,Hirotomo Noda ,Ross Findlay ,Takanao Saiki ,Masahiro Nishimura ,Kei Shirai ,Rina Noguchi ,K Kitazato ,Daiki Yamamoto ,R C Greenwood ,M Fujimoto ,Hiroshi Takeuchi ,Y Shimaki ,Yu Kodama ,T Morota ,Shota Kikuchi ,A Tsuchiyama ,Masanao Abe ,Akiko Miyazaki ,Saichi Hosoda ,Kentaro Hatakeda ,T Iwata ,Masateru Ishiguro ,Manabu Yamada ,Naoko Ogawa ,Go Ono ,Ryota Fukai ,Hikaru Yabuta ,Ikuya Sakurai ,Koji Matsumoto ,Makoto Kimura ,Tatsuhiro Michikami ,Kasumi Yogata ,Kunihiko Yoshikawa ,Naoyuki Hirata ,Shun Sekimoto ,Koji Wada ,Kazuya Kumagai ,Nozomi Matsuda ,Yuya Hitomi ,Hayato Yuzawa ,Fuyuto Terui ,Yoshiaki Ishihara ,Osamu Mori ,Makoto Yoshikawa ,Hiromichi Soejima ,Naru Hirata ,Masahiro Yasutake ,Kaori Hirahara ,I A Franchi ,Hirotaka Sawada ,Kevin D Mckeegan ,Akira Miura ,Masahiko Hayakawa ,Masahiko Arakawa ,Moe Matsuoka ,K A Mccain ,Kentaro Uesugi ,Satoshi Tanaka ,T Hayashi ,Masayuki Uesugi ,Chisato Okamoto ,Yuzuru Karouji ,Eri Tatsumi ,Aiko Nakato ,Chikatoshi Honda ,Yasuhiro Yokota ,S Watanabe ,Shozo Nakazawa ,Kazunori Ogawa ,Hiroki Senshu ,Noriyuki Namiki ,Miwa Yoshitake ,Seiji Sugita ,Naoya Sakatani ,Hajime Yano ,Shizuho Furuya ,Naoki Shirai ,Rie Honda ,Toru Yada ,A Yamaguchi ,Y Iijima ,Atsushi Fujii ,Masanobu Ozaki ,Hitoshi Ikeda ,Ming‐Chang Liu ,Ikuo Okada ,Ryudo Tsukizaki ,Keisuke Yoshihara ,J Malley ,Yuya Mimasu ,Tetsuya Yamada ,Kosuke Kawahara ,T Okada ,Akihisa Takeuchi ,Yukio Yamamoto ,Naoya Imae ,Takuji Ohigashi ,Ayako Iwamae ,Yuichi Tsuda

doi:10.1038/s41550-022-01745-5

Abstract

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.

Full Text