Trajectory of HAYABUSA Reentry Determined from Multisite TV Observations

The asteroid explorer HAYABUSA reentered into the Earth's atmosphere on 2010 June 13. We made simultaneous TV (television) observations at seven ground sites in order to calculate the trajectories of HAYABUSA and its sample return capsule (SRC), which both reentered into the atmosphere. Our TV observations showed that, after HAYABUSA reentered the atmosphere, the beginning time of its light emission on video was 13:51:57.4 UT at a height of 101.0$\ \pm\ $0.2 km. The end time was 13:52:42.0 UT at a height of 38.6$\ \pm\ $0.2 km. The initial velocity at the beginning was 12.1$\ \pm\ $0.3 km s$^{-1}$, and the entry angle was 9$^{\circ}$. After identifying SRC as separated light emission independent of the mother spacecraft, we analyzed the trajectory of SRC from a height of 52.9 km to 35.7 km based on video images. The actual trajectory of the capsule, determined from the TV observations, was almost the same as the predicted trajectory in terms of the position, velocity, and time. We then calculated the fall spots of the SRC heat shields from the multisite TV observations.