Molecular scattering dynamics at hyperthermal velocities and its impact on low drag satellite

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02346
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 24010:Aerospace engineering-related
• Research Institution: Kobe University
• Principal Investigator: Tagawa Masahito 神戸大学, 工学研究科, 准教授 (10216806)
• Co-Investigator(Kenkyū-buntansha): 横田 久美子 神戸大学, 工学研究科, 助手 (20252794) ; 岩田 稔 九州工業大学, 大学院工学研究院, 准教授 (80396762)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 地球高層大気 / 大気密度 / 衛星大気抵抗 / 超低高度衛星 / 分子散乱

Outline of Final Research Achievements

In this project, angular distribution of scattering atoms on satellite materials was measured in order to reduce atmospheric drag of VLEO satellites. The results showed that the molecular beam scattering from the polyimide surface was dominated by the specular reflection component, while the diffuse reflection component increased for the material irradiated by atomic oxygen. Similar changes were observed for the polyimide exposed to LEO environment on the ISS. The scattering distribution obtained in this experiment was implemented as a scattering model in DSMC calculations to calculate satellite drag. It was shown that the atmospheric drag increased by the exposure to atomic oxygen, and that the drag could be reduced by using a two-dimensional material with a predominant specular reflection component as the surface material.

Free Research Field

宇宙環境工学

Academic Significance and Societal Importance of the Research Achievements

超低軌道（VLEO）領域では大気密度が大きいため、衛星の低抵抗化が重要な設計ポイントとなる。VLEOでの大気分子流れは分子流領域であることから、超低軌道衛星の低抵抗化には航空機とは全く異なる超熱速度希薄流体力学の適用が必要となるが、実験設備がなかったことから世界的にも未踏の学術領域である。本研究では独自のシステムにより超熱分子速度領域の分子散乱を実験的に計測し、低抵抗衛星設計技術の確立を行った。