演題概要

1D-S-1625

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炭素質小惑星リュウグウの化学進化と有機分子レベル高分解能質量分析法

(¹海洋研究開発機構（JAMSTEC）・ ²アメリカ航空宇宙局（NASA）・ ³九大院理)
^o高野淑識¹・ ジェイソンドワーキン²・ 奈良岡浩³

What does the carbonaceous asteroid Ryugu tell us ? The returned sample from Ryugu have been found to be the most primordial material in the Solar System [1]. The carbonaceous sample is rich in organic matter composed of light elements of Carbon (C), Hydrogen (H), Nitrogen (N), Oxygen (O), and Sulfur (S) within a range of up to ~23.7 wt% for total CHN(O)S [2]. Hayabusa2-initial-analysis SOM (Soluble Organic Matter) team have reported the isotopic compositions of those light elements (δ¹³C, δD, δ ¹⁵N, δ ³⁴S; ‰ versus to international standards) with high precision and accuracy on the ultra-small scale [2]. In subsequent analysis, we reported qualitative and quantitative results for a wide variety of organic molecules by using targeted and non-targeted analytical methods. We expected that the key words in surveying the Ryugu are the interaction among “water, organic matter, minerals, and the asteroid history”. Hence, Ryugu is a natural laboratory where ongoing prebiotic chemical evolution is occurring under pristine physico-chemical condition. Here, we highlight latest findings of chemical evolution revealed by the high-resolution mass spectrometry of organic molecules for the returned sample from Ryugu. We believe it is very important to compare our results with the organic astrochemical characteristics of the carbonaceous asteroid Bennu collected by OSIRIS-REx mission.

[1] Tachibana et al., Science (2022); Yada et al., Nature Astronomy (2022).
[2] Naraoka et al., Science (2023) and following references.