Added 1 new A* page:I had to draw the surface of this asteroid close-up for today's page, and as I sat down to do that I realized that the close-up view of what we've seen in most asteroids is kinda boring up close: a fairly smooth dusty surface with the occasional impact crater here and there. So I got to looking around to see if I could find an asteroid with a little more in the way of compelling surface detail, and what came up was 25143 Itokawa, the 535-meter-long asteroid visited by the Japanese probe Hayabusa in 2005. The surface of this asteroid--there are plenty of images on Google Image Search; I'm not going to post them directly because the Japanese space agency JAXA's terms for doing so are unnecessarily complicated and restrictive (just make them copyright-free like NASA, guys; sheesh!)--has a spiky appearance, speckled as it is with small to large rocks and boulders, some as large as 25 meters wide, and perhaps weighing in themselves as much as 50,000 tons. Much more interesting to look at!
The asteroid is what is known as a "rubble pile": rather than being a solid chunk of rock, it is a low-density accumulation of smaller rocks and dust, rather loosely held together by their own gravity. A study of the surface sample returned to Earth by Hayabusa suggested that the rubble may be pieces of a larger asteroid that had shattered, then collected together about 8 million years ago. This article goes into detail on 25143 Itokawa's surface and composition, and mentions that "rubble pile" asteroids could be very handy for mining, since you don't have to cut them apart, but can just lift off pieces of the size you want.
I don't necessarily mean for the asteroid in our A* story here to be a pure "rubble pile," but I do like the look of having surface rubble like that.
Incidentally, here's an interesting photo in which the Hayabusa probe captured its own shadow crossing the face of the asteroid.
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