Rosetta’s stone - September 08, 2008
European space probe Rosetta flew by the Steins asteroid on Saturday and totally failed to take high resolution pictures of it.
As the European Space Agency notes right at the bottom of its very upbeat press release:
Science team members noted that the Narrow Angle Camera (NAC) appears to have switched to safe mode a few minutes before closest approach, but switched back on after a few hours.
AP knows the truth: Rosetta is “an unlucky tourist” that has produced “a second-rate image because the hi-res camera failed”.
Still, the images that were produced are quite nice, if unsurprisingly asteroid-esque. Particularly excited is Bad Astronomy’s Phil Plait:
It’s literally a diamond in the rough! Man, that’s weird. Asteroids of this size range (Steins is about 5 kilometres (3 miles) across) can theoretically be pretty much any shape; the gravity of an object that size isn’t strong enough to morph the rock into a sphere.
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But a diamond shape? Wow.
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And it gets weirder. Steins has a ginormous crater on it, spanning 1.5 km (1 mile) of its surface. That’s pretty big, and the impact that created it must have been impressive. In general, if Steins is a solid chunk of rock, an impact that large could have shattered it, or at least infused it with cracks. That makes me wonder if Steins isn’t solid, but is instead a rubble pile; a pile of loose chunks held together by its own weak gravity.
ESA’s Uwe Keller is also intrigued by the craters. “There is also a chain of seven craters that we would not expect to see on such a small body,” he says (Daily Telegraph). “We normally see craters like this on moons like our own. We have to look at why they are there, but clearly Steins has a complex collision history. The colour of Steins is essentially grey but it is a little bit reddish. It is also larger than we expected.”
Of course, given this is an asteroid it’s obligatory to say any new data could help us understand the formation of the solar system. But Gerhard Schwehm, the ESA mission manager, tells it very nicely when he tells AP, “Dead rocks can say a lot.”
