The European Rosetta mission is on its way to rendezvous with a comet (and deploy a lander!), but on its way there it’s making a flyby of an asteroid. Called 2867 Steins (wondering about the title of this post?), the rock is about 5 kilometers across (roughly as big as the mountains I see out my window), and Rosetta will pass just 800 kilometers from it. The encounter will happen on Friday September 5 at 20:58:16 CEST (18:58 UT or 14:58 Eastern US time).
Emily, as always, has the info. That link goes to a specific blog post, but keep her blog handy on Friday and this weekend. She’ll be posting more, as will I, including pictures from the flyby. Rosetta also has a blog of its own, which will no doubt have even more.
September 4th, 2008 at 3:16 pm
Thanks for bringing the full RSS feed back!
September 4th, 2008 at 3:24 pm
Yes, I was wondering about the title of the post. Why would a flyby “expel” an asteroid? Then you explained it. Thanks for the groaner.
September 4th, 2008 at 3:24 pm
Hey Phil, here’s a question about asteroids… they always appear “weathered” (no sharp edges, rounded features). Is this appearance due to billions of years of small impacts wearing away the edges, or did they originally form in this shape?
You would think that a rock in a vacuum would not change appearance very much.
September 4th, 2008 at 3:34 pm
As a non-astrophysicist I always assumed it was because that asteroids formed from big lumps of molten magma or whatever and they just coalesced into a blob as they cooled due to the not-really-magic of surface tension.
September 4th, 2008 at 3:53 pm
1 Stein is more than enough. Why would we want 2867 Steins?!? *shiver*
September 4th, 2008 at 10:06 pm
So how does the Rosetta Mission flyby expel an asteroid? It might be better to first ask why did the Rosetta Mission eat the asteroid?
September 4th, 2008 at 10:56 pm
Thanks for the heads up Phil
September 5th, 2008 at 3:02 am
I went to link. No explanation of “expel”.
I’ve read, somewhere, and heard on night talk shows, that an object (from Earth) can change an asteroid’s trajectory, without touching it. Is that concept what this is about?
September 5th, 2008 at 8:03 am
Don: The asteroid has “Steins” in the name, and Phil is making a reference to Ben Stein, host of the pro-creationism hatchet job movie “Expelled”.
Yes, it’s a very weak joke. But thank you for your question, which prevented me from making an even weaker bathroom joke about expelling asteroids.
September 5th, 2008 at 10:00 am
[…] European spacecraft Rosetta will pass by asteroid Steins today, giving us our first close-up views of this mountain-sized rock. But far and away the most […]
September 5th, 2008 at 10:13 am
I’m missing something in my translation - why isn’t the probe expelled (more than the asteroid)?
Why not tension ruling both processes, gravity trying to collect the initial material and later redistributing the part of impact weathered material that doesn’t escape Stein’s gravitation?
Btw, the initial material is AFAIU grains, once radiative melted or not, not molten larger bodies. Dunno if impact heating manages to melt the larger bodies, I thought it was the then higher radioactivity that did most of that assuming the body becomes large enough.
Also, IIRC impact processes tends to wear down topography in most cases. [Even if hardy grains can form caustics, i.e. sharp points and pillars, in an impact flow. Impact weathering preferentially from a set of smaller angles (due to the geometry of an extended body) will still make them eventually disconnect - fall off. So the process is emergent smoothening, for small impacts.] For example, sand blasting smooths.
Steins is AFAIU a rare asteroid, with spectra indicating that it comes from a larger body that had managed to melt and separate different materials. So perhaps it can be round (which I hear it likely is, from reflection studies) for several possible reasons. I would love to have an astronomer explain and sort out these processes.
September 5th, 2008 at 1:00 pm
Hey I wonder if anyone else took a look at Emily Lakdawalla’s blog from the 25 Aug 08. There is an animation showing Steins moving in the field but there is another bright object that you can see between the 2 shots appearing to trail Steins. Here (maybe is the link)
http://www.planetary.org/blog/article/00001616/
September 6th, 2008 at 3:57 pm
Too bad the camera went into safe mode as the probe approached. Is it equiped with Windows95?