I actually know this from some browser game, I've played years back.
Everytime there was a space fight, there was some debris left which could be collected. Actually this is a pretty nice idea, because if you have space fighters built out of some material, that material would be still there if the fighter gets destroyed.
The idea is maybe that debris will stay and can be collected.
Space Fights can happen either in the orbit of an asteroid (where it may get collected automatically) or it can happen somewhere in space - where a debris field will be created which can be harvested by some specially made ships maybe.
What do you think about the idea?