A low risk reentry: looking backward to step forward

Low risk reentry vehicles, as recently proposed, may represent the right answer for the future demands of space exploration, Space Station operations, and space tourism. In this paper the low risk features of sharp reentry vehicles are discussed. In particular, the concept of boundary layer thermal protection is illustrated with reference to a three-dimensional nose-cone geometry. The flow field around the fuselage tip is found by Computational Fluid Dynamics (CFD) calculations. The critical aerothermal conditions in the velocity-altitude plane are identified, in terms of the highest temperature surface points that belong to the Thermal Protection System (TPS) (i.e. the stagnation point of the fuselage tip) and to the structural material (i.e. the point at the junction of the TPS with the structure). Typical reentry trajectories for a concept vehicle are computed according to this new descent philosophy, which comply with thermal boundaries. The influence of the chosen aerodynamic solutions on reentry heating and on downranges and crossranges is then discussed.