Titolo della tesi: SOME ANALYSIS ON THE ANOMALIES OCCURING DURING ENTRY IN MARTIAN ATMOSPHERE
Schiaparelli was a re-entry capsule used in the framework of the ESA ExoMars mission and had a serious anomaly during the descending phase and was destroyed at the impact on the Martian Surface. The failure was generated by unexpected oscillations of the parachute occurring during the parachute deployment (a phenomenon called areal oscillations): these fast oscillations saturated the gyro sensors so that attitude of the capsule was wrongly determined, and the on-board computer gave wrong recovery commands. The thesis is to perform an analysis of the Schiaparelli mission, reproducing the different re-entry phases to eventually understand the reasons of the mission failure by using CFD analysis of the capsule and parachute during the entry phase into the Mars atmosphere. A preliminary step was the validation of the numerical codes by comparison with existing examples taken from the scientific literature. After this step, the Schiaparelli environment conditions are simulated considering the composition of the Mars atmosphere and the nominal entry conditions of the capsule with chemical reactions. The wake after the capsule is computed and this represents the flow encountered by the parachute during its deploying phase. This phase is analysed considering approximated analytical modes as well as by numerical investigation with ideal gas and perfect gas. The numerical investigation of the aereal oscillations and final trajectory of the Schiaparelli Parachute deployment with various angles of attack using chemical components in Martian atmosphere has been performed in the last part of this thesis.
Keywords: Computational Fluid Dynamics, Mars atmosphere, Aereal oscillations, Chemical, Trajectory, Angle of attack.