The texture used for the asteroid was WHITE2.JPG with UV repeats of 2 and 4. The bump map was BASIC.JPG with UV repeats of 8 and 8, with an Amp of 0.1. Both image files are part of the Rockgen distribution.
As mentioned in the 'Rocks' tips page, Procedural Granite is a good place to start for rock textures. Unfortunately, using procedurals tends to increase render time. When working on the lighting for this scene, I was doing a lot of test renders with raytracing turned on (to check how the shadows were falling), and began to get impatient. So, I painted a plane with the same granite procedural as the asteroid, rendered it, and took it into Photoshop. I made it into a tileable texture, messed around with the colors a bit, and added some noise. Once back in tS, I had to fiddle around with the UV repeats for a while to get it to look similar to the original procedural, but once I got it right, it was worth it. My render times had been noticably reduced, and the noise and color variances I added really enriched the texture.
There are three lights in this scene:
The reason for having the first two lights instead of just one shadowcasting light is that the second non-shadowcaster allows more detail to be shown in the shadow region. Why not just increase the Ambient value of the texture? Increasing the Ambient value will increase visibility in the shadow region, but to me, it looks too 'flat'. It's a subtle difference, but it's the subtleties that add realism.