Observational study of mass transport unevenly distributed in terrestrial planetary and satellite systems by mass spectrometry of ejected material

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04039
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: Osaka University
• Principal Investigator: Yokota Shoichiro 大阪大学, 大学院理学研究科, 准教授 (40435798)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 質量分析 / 超高層大気 / 月 / 外気圏 / 大気散逸 / スパッタリング

Outline of Final Research Achievements

Using mass spectrometry data from Earth and lunar orbiting spacecraft, I evaluated the mass transport occurring in the Earth-Moon system. A method was developed to quantitatively identify nitrogen ions and molecular ions as well as oxygen ions that escape from the Earth based on observation data from the Arase spacecraft. Using the calculated composition ratios of dissipated ions, I showed that the ionospheric supply source gradually shifts to lower altitudes and latitudes with the passage of magnetic storms. Using observation data from the lunar explorer KAGUYA, I investigated the distribution of emitted refractory ions and showed that it is possible to distinguish whether the source material is primordial or has undergone evolution. The results were used to examine the observation plan by the mass spectrometer for the Martian Mission Exploration (MMX).

Free Research Field

惑星科学

Academic Significance and Societal Importance of the Research Achievements

宇宙機搭載の質量分析装置によって地球から放出する大気の組成比を求めることで、大気進化の様子を調べた。月から放出する粒子を調べることで、月など小天体の成り立ちの情報が得られることを示した。火星とフォボスでも同様に構成粒子が放出していることが期待されるため、火星衛星探査計画MMXに搭載する質量分析器の将来観測計画の検討に、この研究成果を利用した。本成果は広く惑星環境の研究に役立つと期待できる。