Primordial aqueous alteration recorded in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu

Creators: Takano, Yoshinori; Naraoka, Hiroshi; Dworkin, Jason P.; Koga, Toshiki; Sasaki, Kazunori; Sato, Hajime; Oba, Yasuhiro; Ogawa, Nanako O.; Yoshimura, Toshihiro; Hamase, Kenji; Ohkouchi, Naohiko; Parker, Eric T.; Aponte, José C.; Glavin, Daniel P.; Furukawa, Yoshihiro; Aoki, Junken; Kano, Kuniyuki; Nomura, Shin-ichiro M.; Orthous-Daunay, Francois-Regis; Schmitt-Kopplin, Philippe; Furusho, Aogu; Hashiguchi, Minako; Fukushima, Kazuhiko; Aoki, Dan; McLain, Hannah L.; Elsila, Jamie E.; Graham, Heather V.; Eiler, John M.¹; Hertkorn, Norbert; Ruf, Alexander; Wolters, Cédric; Isa, Junko; Vuitton, Véronique; Thissen, Roland; Sakai, Saburo; Sugahara, Haruna; Mita, Hajime; Chikaraishi, Yoshito; Yoshikawa, Takaaki; Tanaka, Satoru; Morita, Mayu; Onose, Morihiko; Araoka, Daisuke; Kabashima, Fumie; Fujishima, Kosuke; Sato, Hajime; Yamazaki, Tomoya; Kimura, Yuki; Yurimoto, Hisayoshi; Nakamura, Tomoki; Noguchi, Takaaki; Okazaki, Ryuji; Yabuta, Hikaru; Sakamoto, Kanako; Yada, Toru; Nishimura, Masahiro; Nakato, Aiko; Miyazaki, Akiko; Yogata, Kasumi; Abe, Masanao; Okada, Tatsuaki; Usui, Tomohiro; Yoshikawa, Makoto; Saiki, Takanao; Tanaka, Satoshi; Terui, Fuyuto; Nakazawa, Satoru; Watanabe, Sei-ichiro; Tsuda, Yuichi; Tachibana, Shogo

1. California Institute of Technology

Abstract

We report primordial aqueous alteration signatures in water-soluble organic molecules from the carbonaceous asteroid (162173) Ryugu by the Hayabusa2 spacecraft of JAXA. Newly identified low-molecular-weight hydroxy acids (HO-R-COOH) and dicarboxylic acids (HOOC-R-COOH), such as glycolic acid, lactic acid, glyceric acid, oxalic acid, and succinic acid, are predominant in samples from the two touchdown locations at Ryugu. The quantitative and qualitative profiles for the hydrophilic molecules between the two sampling locations shows similar trends within the order of ppb (parts per billion) to ppm (parts per million). A wide variety of structural isomers, including α- and β-hydroxy acids, are observed among the hydrophilic molecules. We also identify pyruvic acid and dihydroxy and tricarboxylic acids, which are biochemically important intermediates relevant to molecular evolution, such as the primordial TCA (tricarboxylic acid) cycle. Here, we find evidence that the asteroid Ryugu samples underwent substantial aqueous alteration, as revealed by the presence of malonic acid during keto–enol tautomerism in the dicarboxylic acid profile. The comprehensive data suggest the presence of a series for water-soluble organic molecules in the regolith of Ryugu and evidence of signatures in coevolutionary aqueous alteration between water and organics in this carbonaceous asteroid.

Copyright and License

© The Author(s) 2024. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Acknowledgement

The Hayabusa2 project has been organized by JAXA (Japan Aerospace Exploration Agency) with DLR (German Space Center), CNES (French Space Center), NASA (National Aeronautics and Space Administration) and ASA (Australian Space Agency). Preliminary results of this study were partly reported at the Hayabusa symposium and Lunar and Planetary Science Conference (LPSC). This study was partly conducted by the official collaboration agreement through the joint research project with JAMSTEC, Keio University and HMT Inc. The authors thank Dr. M. Tomita and Mr. K. Hashizume for their constructive advice and technical cooperation. This research is partly supported by the grant from the Japan Society for the Promotion of Science (JSPS) with KAKENHI numbers; 21KK0062 (Y.T.), 21J00504 (T.K.), 21H04501&21H05414 (Y.O.), 20H00202 (H.N.). J.P.D. and D.P.G. thank NASA for support of the Consortium for Hayabusa2 Analysis of Organic Solubles. This study was conducted in accordance with the Joint Research Promotion Project at the Institute of Low Temperature Science, Hokkaido University (21G008 and 22G008 to Y.T., Y.O., H.N.).

Contributions

Y.Takano, H.N., J.P.D. designed the outline and entire working flow in this study. H.N. and Y.Takano conducted sequential solvent extraction and distributed the SOM samples. Y.Takano, K.Sasaki, H.S. and T.K. conducted the analysis of high-resolution mass spectrometry. N.O.O., Y.Takano, and N.O. conducted the analysis of elemental and isotopic compositions. N.O.O. and N.O. provided the series of authentic C, N isotope standards. H.N. provided the series of H, O isotope standards. T.Yoshimura and Y.Takano lead the primary description of water-extractable cations and anions. Y.O. and T.K. lead the primary surveys of N-heterocycles. E.T.P., K.Hamase and J.C.A. lead the primary surveys of amino acids and amines. D.P.G. and J.P.D. assessed the organic feature between CI and CM type with Ryugu profiles. Y.F., S.M.N., J.Aoki, K.K. performed small-scale analysis of UV spectra and SALDI mass spectrometry. P.S. and F.R.O.D. lead the non-target comprehensive molecular survey and chemical assignments. H.N., Y.Takano, J.P.D. designed the SOM scheme during the initial analysis timelines (~31-May-2022). S.Tachi, H.Yurimoto, T.Nakamura, T.Noguchi, R.O., H.Yabuta, K.Sakamoto lead the initial analysis processes. M.A., T.Yada, M.N., K.Y., A.N., A.M., T.O., and T.U. curated samples. M.Y., T.S., S.Tana, F.T., S.Nakazawa, S.W., and Y.Tsuda contributed to the sample collection at Ryugu. The Hayabusa2-initial-analysis SOM team members are shown in this report. All authors discussed the results, and commented on the manuscript.

Data Availability

We declare that all these database publications are compliant with ISAS data policies (www.isas.jaxa.jp/en/researchers/data-policy/). The Hayabusa2 project is releasing raw data on the properties of the asteroid Ryugu from the Hayabusa2 Science Data Archives (DARTS, https://www.darts.isas.jaxa.jp/planet/project/hayabusa2/) for Optical Navigation Camera (ONC), Thermal InfraRed Imager (TIR), Near InfraRed Spectrometer (NIR), LIght Detection And Ranging (LIDAR), SPICE kernels, and PDS4.

Supporting information

Conflict of Interest

The authors declare no competing interests.

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