Autonomous optical guidance and navigation strategy around a small body

An impending demand for exploring small bodies such as comets and asteroids initiated the Japanese MUSES-C mission to the near-Earth asteroid Nereus, where it will touch down on the surface. Autonomous optical guidance and navigation strategies around the asteroid is discussed. An aligned intercept guidance that enables the approach from the prescribed direction is built, together with some important guidance properties associated with it. Among them, a combined range-estimation technique using corrections without a range sensor is derived. The robust feature of the closed-loop guidance scheme is stressed. For the first time concrete strategies for such missions to small bodies are presented. Some comprehensive numerical illustrations, including gravity effects, are given from the MULSES-C mission to support the discussion.