First, a video (you should definitely watch it in full-screen, or look at this high-resolution copy. The fireworks are beautiful):
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That was the Japanese spacecraft Hayabusa (Japanese for “peregrine falcon”), returning to Earth two days ago after a seven year voyage. It went to explore an asteroid called 25143 Itokawa, which orbits the Sun at an avergae distance a bit further than the Earth but closer than Mars.
Lots of other spacecraft have flown close by asteroids to look at them before, but Hayabusa did something special: it actually landed on the asteroid briefly, so it could collect a sample and bring it back to Earth. This is the first time that a manmade machine has landed on a celestial body other than the Moon and returned home, which is a pretty exciting first.
The plan was for the craft to fire some metal pellets into the surface of the asteroid, and catch the debris thrown up by the impact to bring back for study. Unfortunately though, a problem with the firing mechanism may mean that the pellets weren’t fired (it can be hard to be sure what’s going on on a robotic craft a hundred million kilometres from home). But even if they didn’t fire, it’s possible that the craft itself threw up enough dust to catch - the pellets were to make absolutely sure - so there’s a chance we’ll have a usable sample anyway.
