Nanophase iron particles (npFe⁰) are generated on the surface of airless bodies by space weathering and can alter surficial optical properties substantially. However, the details of their formation pathways are still unclear. Here we use impact glasses returned from the Moon by Chang’e-5 to distinguish the relative contributions of solar wind irradiation and (micro)meteorites impacts to the production of different-sized npFe⁰. We show that solar wind irradiation can solely produce small npFe⁰, via implantation of solar wind ions into the topmost grain surfaces. On the other hand, (micro)meteorite impacts produce directly large npFe⁰ in melts, through impact-triggered disproportionation reaction or thermal decomposition. These nanoparticles are also capable to further coalesce into micrometre-sized Fe⁰ particles during impacts. These findings can help in predicting the space-weathering behaviour of regions exposed to different space environments.

纳米相铁颗粒（npFe ⁰ ）是通过空间风化在无空气物体的表面产生的，并且可以显着改变表面光学特性。然而，它们形成途径的细节仍不清楚。在这里，我们使用嫦娥五号从月球返回的撞击玻璃来区分太阳风辐射和（微）陨石撞击对不同尺寸的npFe ⁰ 产生的相对贡献。我们表明，通过将太阳风离子注入最顶部的颗粒表面，太阳风照射只能产生小的 npFe ⁰ 。另一方面，（微）陨石撞击通过撞击引发的歧化反应或热分解，在熔体中直接产生大的npFe ⁰ 。这些纳米颗粒还能够在撞击过程中进一步聚结成微米大小的 Fe ⁰ 颗粒。这些发现有助于预测暴露于不同空间环境的区域的空间风化行为。