2022 Fiscal Year Final Research Report
Evolutions of the icy moon surface and interior probed by the long-term plasma space weathering experiment
| Project/Area Number |
20H01956
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 17010:Space and planetary sciences-related
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
Kimura Tomoki 東京理科大学, 理学部第一部物理学科, 准教授 (50578804)
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| Co-Investigator(Kenkyū-buntansha) |
仲内 悠祐 国立研究開発法人宇宙航空研究開発機構, 宇宙科学研究所, 招聘研究員 (20812514)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 氷天体 / 内部海 / プラズマ / 宇宙風化 |
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| Outline of Final Research Achievements |
The key to the occurrence age of the icy body interior ocean is to determine the surface age, at which the interior ocean material erupted and accumulated on the surface. However, this has not yet been solved because direct analysis of the surface material is still technically impossible. This study addressed this problem by focusing on space weathering, which is the alteration of surface materials caused by the irradiation of space plasma. A plasma irradiation device that reproduces space weathering was completed, and irradiation experiments were conducted on salt samples. The surface space weathering was quantitatively correlated with surface age, and the results were compared with spacecraft and telescope observations. Quantitative correlation between the weathering of surface materials and the surface age, and comparison with spacecraft and telescope observations, revealed the existence of relatively new geological units with the interior ocean eruptions within 2000 years.
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| Free Research Field |
惑星圏物理学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究で明らかになった表出年代は、内部海がつい最近まで活発に水を噴き上げ存在していたことを意味する。これは氷天体が形成されたあとから現在に至るまで安定的に内部海を保持し、生命を育みうる環境を維持してきたことを支持する重要な結果である。また、内部海から噴出された水以外の塩等の物質が、天体進化の時間スケールよりも十分短い時間で表層において分解されてしまうことを示した。これは塩が噴出したばかりの海水の組成や、若い地形に対応する重要なトレーサーになることを意味する。将来の氷衛星探査JUICE（ESA）では、上記の塩を探査することで内部海の噴出の活動度や海水環境の推定に寄与することが期待される。
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