The formation of a unique microstructure of minerals on the surface of airless bodies is attributed to space weathering. However, it is difficult to distinguish the contributions of meteorite impacts and solar wind to the modification of lunar soil, resulting in limited research on the space weathering mechanism of airless bodies. The thermochemical reactivity of troilite can be used to distinguish the contributions of impact events and solar wind to the modification of lunar soil and provide evidence for space weathering of lunar soil. We examined the structure of troilite particles in the Chang’e-5 lunar soil and determined whether an impact caused the thermal reaction. Microanalysis showed that troilite underwent substantial mass loss during thermal desulfurization, forming a crystallographically aligned porous structure with iron whiskers, an oxygen-rich layer, and other crystallographic and thermochemical evidence. We used an ab initio deep neural network model and thermodynamic calculations to conduct experiments and determine the anisotropy and crystal growth of troilite. The surface microstructure of troilite was transformed by the thermal reaction in the vacuum on the lunar surface. Similar structures have been found in near-Earth objects (NEOs), indicating that small bodies underwent the same impact-induced thermal events. Thus, thermal reactions in a vacuum are likely ubiquitous in the solar system and critical for space weathering alterations of the soil of airless bodies.

中文翻译：

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月壤的真空热蚀变：来自嫦娥五号样品中锭石铁须的证据


矿物在无气物体表面形成独特的微观结构归因于太空风化。然而，难以区分陨石撞击和太阳风对月壤改造的贡献，导致对无气天体空间风化机制的研究有限。锭石的热化学反应性可用于区分撞击事件和太阳风对月壤改性的贡献，为月壤的空间风化提供证据。我们研究了嫦娥五号月壤中 troilite 颗粒的结构，并确定了撞击是否导致了热反应。微量分析表明，锭石在热脱硫过程中经历了大量的质量损失，形成了一个具有铁须的晶体学排列的多孔结构、富氧层以及其他晶体学和热化学证据。我们使用 ab initio 深度神经网络模型和热力学计算进行实验并确定 troilite 的各向异性和晶体生长。锭石的表面微观结构是通过月球表面真空中的热反应而改变的。在近地天体 （NEO） 中也发现了类似的结构，这表明小天体经历了相同的撞击引起的热事件。因此，真空中的热反应在太阳系中可能无处不在，并且对于无气天体土壤的太空风化变化至关重要。