月表太阳风和粒子辐射环境--“嫦娥四号”观测新结果

The Solar Wind and Particle Radiation Environment on the Surface of the Moon-New Observations from Chang’E-4

太阳风、太阳高能粒子、银河宇宙线几乎可以无阻碍地到达月面,与月表发生相互作用。太阳风粒子以能量中性原子的形式被月壤散射,其过程与太阳风状态、月表电磁环境、局部地形、月壤特性等因素均有关系;银河宇宙射线、太阳高能粒子与月壤相互作用,产生以中子和伽马射线为主的反照辐射,形成特殊的月表粒子辐射环境。文章介绍了“嫦娥四号”首次在月球背面原位所测量的能量中性原子、粒子辐射环境,分析了月面ENA的能谱等特性、月球微磁层存在的观测证据及月面辐射环境的构成及其随时间的变化。结果表明,月表能量中性原子观测为认识太阳风与月球的相互作用,这为研究月球微磁层内部结构及成因提供了新的视角;而月面辐射环境的测量为未来月球探测中航天员和设备的安全保障提供了重要依据。

The solar wind,solar energetic particles and the galactic cosmic rays can reach the Moon almost unhindered,and interact with the lunar surface.The solar wind is partly scattered by the lunar regolith as hydrogen energetic neutral atoms,and the solar wind can also sputter heavy energetic neutral atoms out of the lunar regolith as well.While the albedo radiation,resulting from impact of the solar energetic particles and the galactic cosmic rays on the lunar regolith,are mainly composed of neutrons and gamma rays,features of the lunar surface radiation environment.The first ever in situ measurements of energetic neutral atoms and particle radiation have been carried out by Chang’E-4 on the lunar farside.Results reveal that a mini-magnetosphere is formed in the vicinity of the Moon,suggesting ENA is a new perspective to study the solar wind-Moon interaction.While the radiation measurements provide valuable information to guarantee the health of future robotic or manned missions to the Moon.