S1904-1-2 Reentry Flight of the Hayabusa Sample Return Capsule and Fireball Radiation Observation

Abstract

Hayabusa sample return capsule (SRC) enters the earth atmosphere directly from the interplanetary transfer orbit with velocity over 12 km/s. Due to the extremely high aerodynamic heating up to 15 MW/m^2 exerted on the SRC, the total radiation from the SRC surface and the shock layer is estimated to be -4 to -6 visual magnitude from the ground 100 km apart. The radiation will give us a lot of information of surface phenomena and the interaction between the heatshield material and the high enthalpy air. In the present paper the reentry flight of the Hayabusa SRC and the development of the heatshield are briefly overviewed, and a preliminary ground spectroscopic experiment for correlating the surface phenomena and the radiation spectra is reported preparatory to the actual reentry of the SRC.