The design of reusable aerospace vehicles is a challenge that the aerospace industry has been pursuing for several years in order to reduce the cost of access to space and the environmental impact also in terms of orbital debris. The Space Rider programme of the European Space Agency (ESA) falls within the framework of such initiatives. Among the greatest challenges for this type of mission is the design of the Guidance, Navigation & Control (GNC) subsystem for the atmospheric re-entry phase. This subsystem is responsible for collecting and processing data from onboard sensors so that the state of the spacecraft can be used to generate a feasible trajectory in compliance with mission requirements.