We analyzed photographic observations of the re-entry of the Hayabusa
spacecraft and capsule over Southern Australia on June 13, 2010, 13:52 UT.
Radiometric measurements of the brightness of the associated fireball were
obtained as well. We derived the trajectories and velocities of the spacecraft,
its four fragments and the capsule. The capsule trajectory was within a few
hundred meters of the trajectory predicted by JAXA prior the re-entry. The
spacecraft trajectory was about 1 km higher than the capsule trajectory. Two
major fragments separated from the spacecraft at a height of about 62 km with
mutual lateral velocity of 250 m/s. The maximum absolute magnitude of the
fireball of -12.6 was reached at a height of 67 km. The dynamic pressures
acting on the spacecraft at the fragmentation points were only 1 - 50 kPa. No
spacecraft fragment was seen to survive below the height of 47 km. The integral
luminous efficiency of the event was 1.3%. As expected, the capsule had a very
low luminous efficiency and very low ablation coefficient. The ablation
coefficients and masses of the major spacecraft fragments are discussed.Comment: Accepted for publication in PASJ, 16 pages, 8 figures, 5 table
