Send Leia up towards the top of the atmosphere, use her tractor beam to pull the large asteroid on the right side to knock the smaller asteroid next to it. This should pull the asteroid down into the atmosphere, taking out the pig and destroying the AT-AT. Now fling the next Leia straight ahead at the radar to pull it down. This should finish the level, but you need to damage enough for reach the target score.
See Video Walkthrough.