Because of their excellent olfactory sense, dogs are often used to find bombs, mines, drugs, or people buried by avalanches. For such applications, autonomous mobile robots could be used in the future. Electronic sensors already exist for a wide variety of substances, and are still being actively researched. Mobile robots are an important area of research, too. But beyond a good sensor and a suitable robotic platform, a third component is required: odor source localization algorithms – and due to the complex propagation of odor molecules in the air, tracking down odor sources is still a big challenge.