Direct observation of organic molecules in asteroid ryugu revealed by high-resolution atomic force microscope

A diverse variety of organic matter exists in space. Since these extraterrestrial organic materials preserve chemical information from the early solar system, their identification has been extensively studied. However, detailed structural information has remained limited. Here we investigate organic matter from the carbonaceous asteroid Ryugu using a high-resolution atomic force microscope (AFM). We directly resolve the chemical structures of individual organic molecules from the asteroid. We find a wide variety of polycyclic aromatic hydrocarbons (PAHs), many of which are unexpectedly large in size. The largest one is composed of approximately 100 fused rings, significantly larger than the extraterrestrial PAHs identified in previous ensemble-level analyses. These PAHs exhibit non-planar structures incorporating five-, six-, seven-, and even eight-membered rings. Such complex structures can be resolved in detail only through single-molecule AFM analysis.