RETALT: Recovery GNC for the Retro-Propulsive Vertical Landing of an Orbital Launch Vehicle

This paper presents the RETALT recovery mission GNC, with a focus on the GNC solutions for the powered descent and landing phase. RETALT is a European Union Horizon 2020 project with the objective of investigating launch system reusability technologies for different classes of vertical take- off vertical-landing vehicles. Launcher reusability is the most effective way of reducing access to space available, but remains a great technical challenge for the European aerospace industry, which lags largely behind its US counterparts. One of the challenges lies in the recovery GNC strategy and algorithms, in particular those of the powered-landing phase, which must enable a precise landing with low fuel-margins and significant dispersions. To tackle this, state-of-the art algorithms based on hybrid Navigation techniques for state estimation, as well as online convex optimization and successive convexification for the design of the guidance GNC sub-function are explored. The proposed GNC solutions were integrated and tested in a high-fidelity simulator and the performance were preliminary assessed.