When Spacecraft Misbehave

Engineers get creative when the error message comes from 50 million miles away.


Hayabusa's Remains


(contd.) That was not the end of the mission’s woes. Instead of “bumping” the asteroid, Hayabusa strangely hovered about 30 feet above it, until scientists sent a command for it to abort so they could try again. Later they realized the spacecraft hadn’t been hovering—it had landed, but failed to fire the two “bullets” designed to chip flakes into a sample collector. Project scientists were hopeful that enough dust had been kicked up to take a sample, so they sealed the container, but attempted one more try at the maneuver. The bullets failed to fire again, and then Hayabusa’s thrusters sprung a leak. The spacecraft went into safe mode, and as it drifted away from Itokawa, all communication was lost.

The team found Hayabusa two months later, as a small blip on a radio-wave screen at the Usuda Deep Space Research Center in Saku City, Japan. It took another four months to fully recover control and reestablish communications. As Hayabusa limped toward Earth powered only by the weakened ion engines, its arrival date was pushed from 2007 to 2010. Some doubted that the spacecraft could make it at all.

“But the Hayabusa spacecraft and the JAXA-led team answered every challenge,” says Yeomans. The spacecraft burned up over southern Australia on June 13, 2010, and the sample container capsule floated intact to the ground as planned and was recovered by scientists (above). Inside the container was about 1,500 grains of dust. In spite of all the near catastrophes, the mission became the first to return samples from an asteroid, providing scientists valuable first-hand study of these solar system objects.

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