安部 正真

リュウグウ試料の分析・研究により，多様な有機物や水，特定の揮発性元素の存在が確認され，太陽系最初期の物質の化学進化の過程，とりわけ有機物や水の起源に関する理解が大きく進展した．一連の研究成果は，チーム内の機器と達成すべき科学目標を中心に研究者同士が有機的に連携することで，極少量の試料からでさえ，多くの科学的知見を得られることを示した．また，試料が地球由来の汚染を受けていない状態で初期記載から実際の分析まで実施できたことは，Ph2KとASRGで培った惑星物質のキュレーション技術全般がもたらした大きな成果である．今後，得られた知見を活かし，惑星物質キュレーションのさらなる高度化を図るとともに，戦略的かつ持続的な惑星物質の分析基盤の構築と人材育成を含む国際的な研究ネットワークの拡充が期待される．

Abstract Understanding the processes of aqueous alteration within primitive bodies is crucial for unraveling the complex history of early planetesimals. To better identify the signs of this process and its consequences, we have studied the heterogeneity at a micrometric scale of the structure of the aliphatic organic compounds and its relationship to its mineralogical environment. Here, we report an analysis performed on two micrometric grains of Ryugu (C0002‐FC027 and C0002‐FC028). The samples were crushed in a diamond compression cell and analyzed using high‐spatial resolution Fourier Transform InfraRed (FT‐IR) hyperspectral imaging measurements conducted in transmission mode. We showed here the spatial distributions of the main components and the structural heterogeneity of the aliphatic organic matter highlighting a micrometer‐scale variability in the methylene‐to‐methyl ratio. Moreover, we connected this heterogeneity to the one of the phyllosilicate band positions. Our findings indicate that the organic matter within Ryugu's micrometric grains underwent varying degrees of aqueous alteration in distinct microenvironments resulting in an elongation of the length of their aliphatic chains, and/or a reduction in their branching and/or cross‐linking.