Cool idea and fun to play. The controls feel very smoth and the game is overall polished.
There does seem to be a 'cheesy' tactic that might need to be addressed in some way. You can find a relatively still asteroid near the drill and pull it in VERY slightly. After it starts moving, go to the side or above it and just start scaling it up. Since it's slow, once it hits the drill and breaks up, the smaller parts are also slow so you have time to increase their size a lot before they hit the drill(in which case I think they again spawn more small parts?). I think it would be better if the asteroid was sold as a whole once it reached the drill.