Landing on small bodies trajectory design, robust nonlinear guidance and control

While common Descent and Landing strategies involve extended periods of forced motion, significant fuel savings could be achieved by exploiting the natural dynamics in the vicinity of the target. However, small bodies are characterized by perturbed and poorly known dynamics environments, calling for autonomous guidance, navigation and robust control. Airbus Defence and Space and the University of Bristol have been contracted by the UK Space Agency to investigate the optimisation of landing trajectories, including novel approaches from dynamical systems theory, and robust nonlinear control techniques. This paper presents these techniques, with an application to the strategic case of a mission to Phobos.