Experimental Estimation of Rear-side Heat Flux of Hayabusa Sample Return Capsule

Abstract

The reentry capsule is one of the key technologies to support the sample return mission from deep space. The optimization of heat shield design is essential to meet to the mass allocation of a reentry capsule, and one of approach to reduce its weight includes a precise prediction of the aerodynamic heating environment at the rear-side heat shield. As an observation of the rear heat shield of “Hayabusa” reentry capsule, overlapped part of single side aluminized polyimide tape remained after the capsule returned to the earth. This fact shows that the actual heat flux during reentry on the rear was much lower than the assumption in the development phase. In this paper, the heat flux on the rear was identified by the heating tests of the polyimide tape on the ablators using the inductively coupled plasma heater. The result indicates that the heat flux on the rear heat shield is less than 2% of the front stagnation point heat flux of “Hayabusa” capsule. The result shows the possibility that the thickness of ablator material for the rear heat shield can be reduced with sufficient margin against the actual reentry environment according to experimentally estimated heat flux.