DATE2026.10.16 #Press Releases
The sodium and chlorine on Ryugu exist in an adsorbed state, not as salt.
Disclaimer: machine translated by DeepL which may contain errors.
—Implications for the synthesis of biomolecules such as amino acids and the supply of water to Earth—
Summary
Takahiro Kawai, a graduate student at the Graduate School of Science, The University of Tokyo (at the time of the research),Professor Yoshio Takahashi, and Professor Keisuke Fukushi of Kanazawa University analyzed the chemical species of elements within the C-type asteroid Ryugu using X-ray absorption near-edge structure (XANES) obtained via synchrotron X-rays.As a result, they discovered that in the liquid water present within Ryugu’s parent body, most of the Na and Cl existed not as salts such as NaCl, but in an adsorbed state on the clay mineral. Furthermore, chemical equilibrium calculations taking this into account indicated that the water-mediated metamorphism within Ryugu’s parent body proceeded under strongly basic and strongly reducing conditions. Such a water environment is conducive to the abiotic synthesis of bioorganic compounds such as amino acids and nucleic acid bases.It is also suggested that Ryugu’s aqueous environment is rich in hydrogen gas, indicating that Ryugu underwent metamorphism beneath the ice on the surface of its parent body and that the loss of water from Ryugu is primarily due to ice sublimation (Figure 1).These findings are expected to contribute to our understanding of the evolution of C-type asteroids and the processes by which water was supplied to the early Earth.
Figure 1: Process of water loss from Ryugu
Based on the water composition revealed in this study, the water on Ryugu is strongly basic and strongly reducing; such an environment indicates that Ryugu underwent metamorphism in a location where hydrogen generated deep underground was capped by ice at the surface of the parent body.
Journals
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Journal name Nature CommunicationsTitle of paper