Macromolecular organic matter in samples of the asteroid (162173) Ryugu
Hikaru Yabuta, George D. Cody, C. Engrand, Yoko Kebukawa, B. T. De Gregorio, L. Bonal, Laurent Rémusat, R. M. Stroud, É. Quirico, L. R. Nittler, Minako Hashiguchi, M. Komatsu, Taiga Okumura, Jérémie Mathurin, E. Dartois, J. Duprat, Yoshio Takahashi, Yasuo Takeichi, A. L. D. Kilcoyne, Shohei Yamashita, Alexandre Dazzi, Ariane Deniset‐Besseau, Scott A. Sandford, Zita Martins, Y. Tamenori, Takuji Ohigashi, Hiroki Suga, Daisuke Wakabayashi, Maximilien Verdier‐Paoletti, S. Mostefaoui, Gilles Montagnac, Jens Barosch, Kanami Kamide, Miho Shigenaka, Laure Bejach, Megumi Matsumoto, Yuma Enokido, T. Noguchi, Hisayoshi Yurimoto, Tomoki Nakamura, Ryuji Okazaki, Hiroshi Naraoka, Kanako Sakamoto, H. C. Connolly, D. S. Lauretta, Masanao Abe, Tatsuaki Okada, Toru Yada, Masahiro Nishimura, Kasumi Yogata, Aiko Nakato, Miwa Yoshitake, Ayako Iwamae, Shizuho Furuya, Kentaro Hatakeda, Akiko Miyazaki, Hiromichi Soejima, Yuya Hitomi, Kazuya Kumagai, Tomohiro Usui, Tasuku Hayashi, Daiki Yamamoto, Ryota Fukai, Seiji Sugita, K. Kitazato, Naru Hirata, Rie Honda, Tomokatsu Morota, Eri Tatsumi, Naoya Sakatani, Noriyuki Namiki, Koji Matsumoto, Rina Noguchi, Koji Wada, Hiroki Senshu, Kazunori Ogawa, Y. Yokota, Yoshiaki Ishihara, Yuri Shimaki, Manabu Yamada, Chikatoshi Honda, Tatsuhiro Michikami, M. Matsuoka, Naoyuki Hirata, Masahiko Arakawa, Chisato Okamoto, Masateru Ishiguro, R. Jaumann, Jean‐Pierre Bibring, Matthias Grott, Stefan Schröder, Katharina A. Otto, C. Pilorget, Nicole Schmitz, Jens Biele, Tra‐Mi Ho, Aurélie Moussi‐Soffys, Akira Miura, Hirotomo Noda, Tetsuya Yamada
Abstract
Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu's parent body.