Actionscript 3, help required, pattern over drawn circle

http://ift.tt/1UeIm4u

This is what I am currently working on, and currently, I'm looking for a way (if any) to basically draw automatic, randomised asteroid belts.

The main idea I have, currently, would be to simply draw a circle with a pattern/stroke of asteroid sprites, but I have no idea how this could be achieved.

Ideally, the width and length of a circle of pattern would be randomised, then the sprites drawn.

Help would be greatly appreciated.

Current code to be found within the deviantart page.