Effects of dust storm and atmospheric waves on Martian atmospheric escape

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K20387
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0204:Astronomy, earth and planetary science, and related fields
• Research Institution: Japan Aerospace EXploration Agency
• Principal Investigator: Masunaga Kei 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, 宇宙航空プロジェクト研究員 (60909521)
• Project Period (FY): 2021-08-30 – 2024-03-31
• Keywords: 火星 / 超高層大気 / 大気流出 / ダストストーム / 大気波動

Outline of Final Research Achievements

From the upper atmosphere of Mars, atmospheric components are escaping into space. Traditionally, atmospheric escape was thought to be strongly influenced by external factors such as the solar wind and solar radiation. However, recent studies have indicated that phenomena occurring in the lower atmosphere also have a significant impact. In this study, we analyzed observational data from periods when dust storms and atmospheric waves occurred on Mars to investigate their effects. As a result, we discovered that the total amount of hydrogen and oxygen atoms in the thermosphere and exosphere of Mars undergoes periodic changes due to the strong influence of dust storms and atmospheric waves. Additionally, we observationally demonstrated that the density of ions in the ionosphere also fluctuates periodically. This suggests that atmospheric escape on Mars is strongly influenced by the lower atmosphere and varies over time.

Free Research Field

宇宙惑星科学

Academic Significance and Societal Importance of the Research Achievements

本研究は、火星の大気流出が従来の太陽風や太陽放射の影響だけでなく、下層大気の現象からも強い影響を受けることを観測的に示した点で学術的に重要である。具体的には、ダストストームや大気波動が火星の熱圏・外気圏の水素原子や酸素原子の総量、電離圏のイオン密度に周期的な変動を引き起こすことを発見し、火星大気のダイナミクスや宇宙への大気流出の理解を深めた。この知見は将来の火星探査や有人火星ミッションにおける環境予測や設計に役立つ可能性がある。