Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites.

T Yokoyama ,Kentaro Hatakeda ,Tomohiro Usui ,L R Nittler ,Manabu Yamada ,Rina Noguchi ,T Kleine ,Yasuko Terada ,Ryudo Tsukizaki ,Ming‐Chang Liu ,T Iwata ,Hiroharu Yui ,Koji Matsumoto ,Noriyuki Namiki ,Hiroshi Naraoka ,R J Walker ,Hajime Yano ,Masanao Abe ,Fuyuto Terui ,Chikatoshi Honda ,Naru Hirata ,Tomoki Nakamura ,Masateru Ishiguro ,Masahiro Nishimura ,A M Davis ,Hiroshi Takeuchi ,Д С Лауретта ,Eri Tatsumi ,Edward Young ,G R Huss ,P Höppe ,Andreas Pack ,Keisuke Yoshihara ,Changkun Park ,Toru Yada ,Hirotaka Sawada ,S S Russell ,Qing‐Zhu Yin ,Tomokatsu Morota ,Masahiko Hayakawa ,Shizuho Furuya ,Yukio Yamamoto ,Kazuko Motomura ,Yuto Takei ,Kiyohiro Ichida ,Martin Bizzarro ,Seiji Sugita ,Marc Chaussidon ,Hiroshi Hidaka ,Shota Kikuchi ,Kazunori Ogawa ,Naoyuki Hirata ,Aiko Nakato ,Yuichi Tsuda ,Makiko K Haba ,C M O'd Alexander ,Yoshinari Abe ,Y Iijima ,Yuki Masuda ,Trevor Ireland ,K Nagashima ,Jérôme Adnot ,Audrey Bouvier ,Kasumi Yogata ,Frédéric Moynier ,Liping Qin ,Ikshu Gautam ,Laurette Piani ,Takaaki Noguchi ,Richard W Carlson ,Katsuyuki Yamashita ,Tsuyoshi Iizuka ,Mariko Morita ,Shogo Tachibana ,Yuya Mimasu ,Kouki Kitajima ,Shigekazu Yoneda ,Byeon‐Gak Choi ,Hitoshi Ikeda ,Go Ono ,Chisato Okamoto ,Tatsuhiro Michikami ,Kosuke Kawahara ,Ai‐Cheng Zhang ,H C Connolly ,Akira Ishikawa ,Kevin D Mckeegan ,Akiko Miyazaki ,Ken‐Ichi Bajo ,Alexander N Krot ,M Wadhwa ,Yuya Hitomi ,Kentaro Terada ,Sei‐Ichiro Watanabe ,Hikaru Yabuta ,Yuri Shimaki ,Atsushi Fujii ,Ayako Suzuki ,Noriyuki Kawasaki ,Yoshiaki Ishihara ,N T Kita ,Hiromichi Soejima ,Maria Schönbächler ,Morihiko Onose ,Makoto Yoshikawa ,S Amari ,Haolan Tang ,Tetsuya Yamada ,Tommaso Di Rocco ,Masanobu Ozaki ,N Dauphas ,T Hayashi ,Izumi Nakai ,Motoo Ito ,Yasuhiro Yokota ,Kei Shirai ,Hirotomo Noda ,Masahiko Arakawa ,Sohei Wada ,Kunihiko Yoshikawa ,Lauren Tafla ,Daiki Yamamoto ,Ryota Fukai ,Yuki Hibiya ,Miwa Yoshitake ,K Kitazato ,Koji Wada ,Takanao Saiki ,Rie Honda ,Akira Miura ,A N Nguyen ,Naoko Ogawa ,Naoya Sakatani ,Shintaro Komatani ,Saichi Hosoda ,Satoshi Tanaka ,Hiroki Senshu ,Hisashi Homma ,Wataru Fujiya ,Shoichi Itoh ,Yuri Amelin ,Naoya Sakamoto ,Ryuji Okazaki ,Kazuya Kumagai ,Moe Matsuoka ,Kanako Sakamoto ,Tatsuaki Okada ,Shozo Nakazawa ,Hisayoshi Yurimoto

doi:10.1126/science.abn7850

Abstract

Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37° ± 10°C, about [Formula: see text] million (statistical) or [Formula: see text] million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above ~100°C. The samples have a chemical composition that more closely resembles that of the Sun's photosphere than other natural samples do.

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