Lunar soil undergoes space weathering and accumulates optically active opaque particles (OAOpq) of different sizes, resulting in a darkening or red shift of the reflectance spectrum. The surfaces of weakly weathered objects exhibit spectral characteristics of strong weathering; these mechanisms are still unclear. The causes of OAOpq in lunar soil are complex, especially for submicrometer particles, which account for the largest mass proportion. We found ubiquitous impact-dispersed Fe–FeS core–shell particles in Chang’e-5 lunar soil impact glass and splatter. The crystal structure, particle size distribution, and chemical composition of OAOpq in the impact glass indicate that these OAOpq consist of sulfides or metals from multiple sources. Thermodynamic evidence, diffusion behavior, and particle dispersion characteristics indicate that impact dispersion is the most likely formation mechanism of these OAOpq. The proposed impact dispersion provides a reason for the large number of OAOpq and the limited products for in situ reactions. This process explains why lunar soil with a low degree of weathering exhibits substantial spectral modification properties. The results provide insights into space weathering of the lunar surface and also imply that impact-dispersed OAOpq may be the primary modification type on asteroid surfaces. The unique chemical properties of Fe–FeS OAOpq also indicate that the lunar regolith has the potential for resource utilization.

中文翻译：

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嫦娥五号月壤撞击玻璃中撞击分散的 Fe-Fe1−xS 核壳颗粒


月球土壤经历空间风化并积累不同尺寸的光学活性不透明颗粒（OAOpq），导致反射光谱变暗或红移。弱风化物体的表面表现出强风化的光谱特征；这些机制仍不清楚。月壤中OAOpq的成因比较复杂，特别是亚微米颗粒质量占比最大。我们在嫦娥五号月壤撞击玻璃和飞溅物中发现了无处不在的撞击分散的 Fe-FeS 核壳颗粒。冲击玻璃中 OAOpq 的晶体结构、粒度分布和化学成分表明这些 OAOpq 由多种来源的硫化物或金属组成。热力学证据、扩散行为和颗粒分散特征表明，冲击分散是这些 OAOpq 最可能的形成机制。所提出的冲击分散为大量 OAOpq 和原位反应产物有限提供了原因。这个过程解释了为什么风化程度低的月球土壤表现出显着的光谱修改特性。这些结果提供了对月球表面空间风化的深入了解，也意味着撞击分散的 OAOpq 可能是小行星表面的主要改性类型。 Fe-FeS OAOpq独特的化学性质也表明月球风化层具有资源利用的潜力。