HIGH LIFT SYSTEMS FOR PLANETARY DESCENT AND LANDING

In this thesis, I present a summary of the work performed in five months at the JPL (Jet Propulsion Laboratory) on the dynamics of autonomous parafoils and other autonomous flight solutions. The growing interest in our solar system icy moons is pushing towards innovative solutions for planetary exploration that can enable missions towards difficult targets on this alien satellites. From this point of view, the analysis of high-efficiency gliding systems (i.e., high lift over drag systems) can identify new and more efficient solutions for terminal descent. The present work follows this trend by studying the advantages of a parafoil for autonomous precision delivery of a probe in the Titan environment. The previous successful mission to Titan, the Huygens probe, used a series of drag-only parachutes to drop the payload (low lift to drag parachute). However, this solution provides a limited maneuverability to negotiate the not well-known environmental conditions (air density and winds) and the possibility of targeting different landing sites of scientific interest, shaping the trajectory accordingly. With a ram-air system (a parafoil) one can fly over different interesting sites, map them ahead of time, and even allow the re-planning of the trajectory to land near the most desirable sites. To analyze all these possibilities, dynamics models of the PADs (Precision Aerial Delivery System), with different degrees of freedom, had to be developed and tested. Three degree-of-freedom models focused on the trajectory development. Six degree-of-freedom models were needed to evaluate the parafoil-payload system overall behavior. Seven to nine degree-of-freedom models were needed to determine the payload-canopy interaction. These models were tested in the relevant environmental conditions on Titan, from the aerodynamics to the wind effect to a noisy sensor reading. As a consequence, the performance of the system trying to follow a trajectory in the uncertain atmosphere was evaluated. To realize these tasks, we relied on the methodologies derived from dynamics system modelling for the related equations of motion, from the aerodynamics to investigate the effect of the forces that enable the descent on Titan, from the GN&C (Guidance, Navigation and Control) to determine the requirements posed by autonomy. Consequently, the aim of this work was to provide a system modeling and simulation framework to ultimately allow the development of a complete GN&C system that will lead to a feasible system design, and which advantages these high lift solutions can bring to future missions to Titan.