Lone3wolf: If I recall it correctly, they're both in the top-left asteroid patch of the system. The map is rotatable up and down, as well as left-right. I found it best to send my ships to the asteroids manually, so they arrive at the correct "height" for their radar to "see" the mine-bases. As soon as they do, they're off and laughing.

elbaz: Thanks for the reply. I finally figured out where it was by watching a walkthrough video. It was in the upper left corner of the asteroid. The problem, as you noted, was that my ships were too low to detect the base on the asteroid. After some trial and error, they finally found it.