Radiometric Temperature Analysis of the Hayabusa Spacecraft Re-entry

Introduction

Hayabusa, an unmanned Japanese spacecraft, was launched to study and collect samples from the surface of the asteroid 25143 Itokawa. In June 2010, the Hayabusa spacecraft completed it’s seven year voyage. The spacecraft and the sample return capsule (SRC) re-entered the Earth’s atmosphere over the central Australian desert at speeds on the order of 12 km/s. This provided a rare opportunity to experimentally investigate the radiative heat transfer from the shock-compressed gases in front of the sample return capsule at true-flight conditions. At these conditions, the total heat transfer to the vehicle has a significant radiative component and this can be estimated by studying the radiation emitted from the shock layer and the hot surface. Such measurements can be compared with numerical simulations of the flow and with results from ground-based testing in shock tunnels and expansion tubes. This in turn leads to a better understanding of the complex thermochemistry occurring within the shock layer and aids in the design of more efficient thermal protection systems for future spacecraft.