i'm supposed to get this during a mission by blowing up an asteroid. I've blown up the enemies nearby, but how do I destroy the asteroid? clicking "attack" on it with my mothership /pilots highlighted doesn't do anything (same with missiles)

Edit: Nevermind, I figured it out. What you have to do is hold "crtrl" down while left clicking on the asteroid in question.

How do you destroy the asteroid caches because I have NOT figured it out.

press ctrl after you've selected your ships and then click on the asteroid. That worked for me.