The European Space Agency’s Rosetta mission¹ has acquired unprecedented measurements of the surface of the nucleus of comet 67P/Churyumov–Gerasimenko (hereafter, 67P), the composition of which, as determined by in situ and remote-sensing instruments, including the VIRTIS instrument², seems to be an assemblage of ices, minerals and organic material³. We performed a refined analysis of infrared observations of the nucleus of 67P carried out by the VIRTIS-M hyperspectral imager. We find that the overall shape of the infrared spectrum of 67P is similar to that of other carbon-rich outer Solar System objects, suggesting a possible genetic link with them. More importantly, we also confirm the complex spectral structure of the wide 2.8–3.6 µm absorption feature populated by fainter bands. Among these, we unambiguously identify the presence of aliphatic organics by their ubiquitous 3.38 µm, 3.42 µm and 3.47 µm bands. This infrared detection of aliphatic species on a cometary surface has strong implications for the evolutionary history of the primordial Solar System and is evidence that comets provide an evolutionary link between interstellar material and Solar System bodies⁴.

欧洲航天局的罗塞塔任务¹对 67P/Churyumov–Gerasimenko（以下简称 67P）彗星的核表面进行了前所未有的测量，其组成由原位和遥感仪器（包括 VIRTIS 仪器）确定²，似乎是冰、矿物质和有机物质的组合³. 我们对 VIRTIS-M 高光谱成像仪对 67P 核的红外观测进行了精细分析。我们发现 67P 红外光谱的整体形状与其他富含碳的太阳系外天体相似，这表明与它们可能存在遗传联系。更重要的是，我们还证实了由较暗波段填充的 2.8-3.6 µm 宽吸收特征的复杂光谱结构。其中，我们通过普遍存在的 3.38 µm、3.42 µm 和 3.47 µm 波段明确识别脂肪族有机物的存在。这种对彗星表面脂肪族物种的红外探测对原始太阳系的进化历史具有重要意义，并且证明彗星提供了星际物质和太阳系天体之间的进化联系⁴ .