I heard a guy moved all the asteroids in one direction at the beginning of each turn using the 1 straight template. I tried it once and didn't care for it too much, but have at it.
That is where it would be a fail. One of the guys who I was talking about with this at my FLGS said it would be better to use a scatter dice and then see which direction they would go because if they collided it would alter their course.