We review our current knowledge of comet 67P/Churyumov–Gerasimenko nucleus composition as inferred from measurements made by remote sensing and in-situ instruments aboard Rosetta orbiter and Philae lander. Spectrophotometric properties (albedos, color indexes and Hapke parameters) of 67P/CG derived by Rosetta are discussed in the context of other comets previously explored by space missions. Composed of an assemblage made of ices, organic materials and minerals, cometary nuclei exhibit very dark and red surfaces which can be described by means of spectrophotometric quantities and reproduced with laboratory measurements. The presence of surface water and carbon dioxide ices was found by Rosetta to occur at localized sites where the activity driven by solar input, gaseous condensation or exposure of pristine inner layers can maintain these species on the surface. Apart from these specific areas, 67P/CG’s surface appears remarkably uniform in composition with a predominance of organic materials and minerals. The organic compounds contain abundant hydroxyl group and a refractory macromolecular material bearing aliphatic and aromatic hydrocarbons. The mineral components are compatible with a mixture of silicates and fine-grained opaques, including Fe-sulfides, like troilite and pyrrhotite, and ammoniated salts. In the vicinity of the perihelion several active phenomena, including the erosion of surface layers, the localized activity in cliffs, fractures and pits, the collapse of overhangs and walls, the transfer and redeposition of dust, cause the evolution of the different regions of the nucleus by inducing color, composition and texture changes.

中文翻译：

---

彗星 67P/CG 核组成及与其他彗星的比较

我们回顾了我们目前对 67P/Churyumov-Gerasimenko 彗核组成的了解，这是从罗塞塔轨道器和菲莱着陆器上的遥感和原位仪器的测量推断出来的。Rosetta 推导出的 67P/CG 的分光光度特性（反照率、颜色指数和 Hapke 参数）在先前太空任务探索的其他彗星的背景下进行了讨论。彗核由冰、有机材料和矿物组成的集合体呈现出非常暗和红色的表面，可以通过分光光度数来描述，并通过实验室测量进行再现。罗塞塔发现地表水和二氧化碳冰的存在发生在由太阳能输入驱动的局部地点，气态冷凝或原始内层的暴露可以使这些物种保持在表面上。除了这些特定区域外，67P/CG 的表面在成分上显得非常均匀，主要是有机材料和矿物质。有机化合物含有丰富的羟基和含有脂肪族和芳香族烃的难熔高分子材料。矿物成分与硅酸盐和细粒不透明物的混合物相容，包括铁硫化物，如硫磺铁矿和磁黄铁矿，以及氨化盐。在近日点附近有几种活动现象，包括表层侵蚀、悬崖、裂缝和坑洞的局部活动、悬垂物和墙壁的倒塌、灰尘的转移和再沉积，