Electron microscopy observations of the diversity of Ryugu organic matter and its relationship to minerals at the micro‐ to nano‐scale
Authors: Stroud Rhonda M. , Barosch Jens , Bonal Lydie , Burgess Katherine , Cody George D. , De Gregorio Bradley T. , Daly Luke , Dartois Emmanuel , Dobrică Elena , Duprat Jean , Engrand Cecile , Harries Dennis , Hashiguchi Minako , Ishii Hope , Kebukawa Yoko , Kilcoyne A. David , Langenhorst Falko , Lee Martin R. , Nittler Larry R. , Quirico Eric , Okumura Taiga , Remusat Laurent , Sandford Scott , Yabuta Hikaru , Abe Masanao , Abreu Neyda M. , Bagot Paul A. J. , Beck Pierre , Bejach Laure , Bland Phil A. , Bridges John C. , Cymes Brittany A. , Dazzi Alexandre , de la Peña Francisco , Deniset‐Besseau Ariane , Enju Satomi , Enokido Yuma , Frank David R. , Gray Jennifer , Haruta Mitsutaka , Hata Satoshi , Hicks Leon , Igami Yohei , Jacob Damien , Kamide Kanami , Komatsu Mutsumi , Laforet Sylvain , Leroux Hugues , Le Guillou Corentin , Martins Zita , Marinova Maya , Martinez James , Mathurin Jérémie , Matsumoto Megumi , Matsumoto Toru , Matsuno Junya , McFadzean Samuel , Michikami Tatsuhiro , Mitsukawa Itaru , Miyake Akira , Miyahara Masaaki , Miyazaki Akiko , Montagnac Gilles , Mostefaoui Smail , Nakamura Tomoki , Nakato Aiko , Naraoka Hiroshi , Nakauchi Yusuke , Nakazawa Satoru , Nishimura Masahiro , Noguchi Takaaki , Ohtaki Kenta , Ohigashi Takuji , Okada Tatsuaki , Okumura Shota , Okazaki Ryuji , Phan Thi H. V. , Rebois Rolando , Sakamoto Kanako , Saiki Takanao , Saito Hikaru , Seto Yusuke , Shigenaka Miho , Smith William , Suga Hiroki , Sun Mingqi , Tachibana Shogo , Takahashi Yoshio , Takeichi Yasuo , Takeuchi Akihisa , Takigawa Aki , Tamenori Yusuke , Tanaka Satoshi , Terui Fuyuto , Thompson Michelle S. , Tomioka Naotaka , Tsuchiyama Akira , Tsuda Yuichi , Uesugi Kentaro , Uesugi Masayuki , Usui Tomohiro , Verdier‐Paoletti Maximilien , Wakabayashi Daisuke , Watanabe Sei‐ichiro , Yada Toru , Yamashita Shohei , Yasutake Masahiro , Yogata Kasumi , Yoshikawa Makoto , Yurimoto Hisayoshi , Zanetta Pierre‐M. , Zega Thomas , Zolensky Michael E. 
Published: January 2024

Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range of morphologies, elemental compositions, and carbon functional chemistries consistent with those of carbonaceous chondrites that have experienced low‐temperature aqueous alteration. Both nanoglobules and diffuse organic matter are abundant. Non‐globular organic particles are also present, and including some that contain nanodiamond clusters. Diffuse organic matter is finely distributed in and around phyllosilicates, forms coatings on other minerals, and is also preserved in vesicles in secondary minerals such as carbonate and pyrrhotite. The average elemental compositions determined by energy‐dispersive spectroscopy of extracted, demineralized insoluble organic matter samples A0107 and C0106 are C100N3O9S1 and C100N3O7S1, respectively, with the difference in O/C slightly outside the difference in the standard error of the mean. The functional chemistry of the nanoglobules varies from mostly aromatic C=C to mixtures of aromatic C=C, ketone C=O, aliphatic (CHn), and carboxyl (COOH) groups. Diffuse organic matter associated with phyllosilicates has variable aromatic C, ketone and carboxyl groups, and some localized aliphatics, but is dominated by molecular carbonate (CO3) absorption, comparable to prior observations of clay‐bound organic matter in CI meteorites.