Chemical evolution of primordial salts and organic sulfur molecules in the asteroid 162173 Ryugu
Toshihiro Yoshimura, Yoshinori Takano, Hiroshi Naraoka, Toshiki Koga, Daisuke Araoka, Nanako O. Ogawa, Philippe Schmitt‐Kopplin, Norbert Hertkorn, Yasuhiro Oba, Jason P. Dworkin, José C. Aponte, Takaaki Yoshikawa, Satoru Tanaka, Naohiko Ohkouchi, Minako Hashiguchi, Hannah L. McLain, Eric T. Parker, Saburo Sakai, Mihoko Yamaguchi, Takahiro Suzuki, Tetsuya Yokoyama, Hisayoshi Yurimoto, Tomoki Nakamura, T. Noguchi, Ryuji Okazaki, Hikaru Yabuta, Kanako Sakamoto, Toru Yada, Masahiro Nishimura, Aiko Nakato, Akiko Miyazaki, Kasumi Yogata, Masanao Abe, Tatsuaki Okada, Tomohiro Usui, Makoto Yoshikawa, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Satoru Nakazawa, Sei‐ichiro Watanabe, Yuichi Tsuda, Shogo Tachibana, Hayabusa2-initial-analysis SOM team, Kenji Hamase, Aogu Furusho, Kazuhiko Fukushima, Dan Aoki, D. P. Glavin, Hannah L. McLain, Jamie E. Elsila, Heather V. Graham, John M. Eiler, Alexander Ruf, François‐Régis Orthous‐Daunay, Cédric Wolters, J. Isa, V. Vuitton, R. Thissen, Haruna Sugahara, Hajime Mita, Yoshihiro Furukawa, Yoshito Chikaraishi, Mayu Morita, Morihiko Onose, Fumie Kabashima, Kosuke Fujishima, Hajime Sato, Kazunori Sasaki, Kuniyuki Kano, Shin‐ichiro M. Nomura, Junken Aoki, Tomoya Yamazaki, Yuki Kimura
Abstract
Abstract Samples from the carbonaceous asteroid (162173) Ryugu provide information on the chemical evolution of organic molecules in the early solar system. Here we show the element partitioning of the major component ions by sequential extractions of salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition of the primitive asteroid. Sodium is the dominant electrolyte of the salt fraction extract. Anions and NH 4 + are more abundant in the salt fraction than in the carbonate and phyllosilicate fractions, with molar concentrations in the order SO 4 2− > Cl − > S 2 O 3 2− > NO 3 − > NH 4 + . The salt fraction extracts contain anionic soluble sulfur-bearing species such as S n -polythionic acids ( n < 6), C n -alkylsulfonates, alkylthiosulfonates, hydroxyalkylsulfonates, and hydroxyalkylthiosulfonates ( n < 7). The sulfur-bearing soluble compounds may have driven the molecular evolution of prebiotic organic material transforming simple organic molecules into hydrophilic, amphiphilic, and refractory S allotropes.