Hayabusa Returns to Earth

At 1400 hours UT on Sunday June 13 a brilliant fireball will appear over Australia. Unlike most fireballs this one won’t be due to a small asteroid but a returning man-made spacecraft. The Japanese Hayabusa (originally called MUSES-C for Mu Space Engineering Spacecraft C) is returning home after a harrowing 7 year mission to a small near-Earth asteroid and back. Harrowing in that almost anything that could go wrong did go wrong. Yet, if all goes well Hayabusa will be the first spacecraft to return samples from an asteroid.

[NOTE: A team from NASA will observe and study the resulting fireball from a NASA research DC-8 aircraft. The airborne team will attempt to broadcast video of the even live. Live video will be shown at 13:45-13:55 UT (9:45-9:55 am EDT).]

Sketch of Hayabusa spacecraft hovering over the surface of asteroid Itokawa during sample collection. Credit: Wikipedia public domain.

Launched in May of 2003, Hayabusa spent just over 2 years traveling to the half-km in diameter Earth-crossing asteroid (25143) Itokawa. In November of 2005 two sample attempts were made. The plan was for Hayabusa to hover a few meters above the asteroid’s surface, fire a small projectile into the surface, and collect any material that was thrown upwards. Due to spacecraft hardware and software control failures mission operators are unsure if any samples were collected. In fact, no one is completely sure what happened when Hayabusa reached the asteroid’s surface due to a loss of contact.

Due to the great work of the mission team, the hobbled spacecraft was coaxed back to Earth in spite of losing its reaction wheels, reaction control system (fine thrusters), and some of its ion thrusters (main propulsion). Regardless of whether Hayabusa successfully lands in Australia on Sunday or whether or not it contains any samples from Itokawa, the mission was highly successful and produced some great data on a small near-Earth asteroid.

Image of asteroid Itokawa by the Japanese Hayabusa spacecraft. Credut: JAXA.