Preliminary Design of the Hybrid Navigation System (HNS) for the CALLISTO RLV Demonstrator

This paper focuses on the preliminary design of the Hybrid Navigation System (HNS) in development for the CALLISTO vehicle. The requirements and boundary conditions derived from the mission design are briefly introduced and their impact on the navigation design is discussed. Subsequently, the baseline architecture for the CALLISTO HNS including the design considerations for its sensor suite will be presented. The HNS features an approach that overcomes limitations of conventional navigation based on purely inertial solutions by fusion of measurements from different sensors. In order to satisfy the requested high accuracy in terms of estimation of vertical and lateral position as well as the flight altitude w.r.t. the landing pad, the sensor suite will comprise radar altimeters and a Differential GNSS (DGNSS) system along with ground-based reference stations. The paper concludes with a preliminary performance study of this HNS configuration through covariance analysis and an outlook on the further development of the system.