Amino acid formation by gamma rays from radionuclides in small bodies in the early solar system

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18648
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: Tokyo Institute of Technology (2023); Yokohama National University (2021-2022)
• Principal Investigator: Kebukawa Yoko 東京工業大学, 理学院, 准教授 (70725374)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 隕石 / 小惑星 / 放射線 / アミノ酸

Outline of Final Research Achievements

Primitive meteorites contain organic matter such as amino acids. It is known that aqueous alteration occurred in these parent bodies due to melting of ice caused by heat from decay of radionuclides in the early stages of the formation of the solar system. Although aqueous alteration process is thought to have contributed to the formation of organic matter, only the effect of heat has been considered, and the direct effect of radiation from radionuclides has not been taken into account. In this study, gamma-ray irradiation experiments were conducted on aqueous solutions containing formaldehyde and ammonia in order to verify the effect of gamma rays due to the decay of radionuclides. The results showed that gamma rays promoted the formation of amino acids. The amount of alanine formed by gamma irradiation showed a linear relationship with the total irradiation dose, independent of the dose rate.

Free Research Field

宇宙化学

Academic Significance and Societal Importance of the Research Achievements

本研究の学術的意義は，太陽系形成初期における有機物の生成過程に関する新たな知見を提供することにある。従来の研究では放射性核種の崩壊による熱の影響のみが考慮されてきたが，本研究はガンマ線の直接的な効果も重要であることを示した。ガンマ線がアミノ酸や糖の形成を促進することが明らかになり，宇宙における有機物の生成過程をより包括的に理解するための基盤を提供する。
社会的意義は，宇宙における有機物の生成過程を解明することにより，地球外生命の可能性や生命の起源研究に貢献し，生命の起源に関する理解を深めることが挙げられる。これにより，科学教育や宇宙探査の意義が広まり，一般の科学への関心を高めることにつながる。