O.K., I have delved into the deepest depths of my memory and cannot remember the title of this game. Here's a description:
It's a side-scroller where you're in a ship and have to shoot through or bomb the surface of the planet to get to other areas. While you're blowing up the surface, small ships attack you. The explosions look similar to Planet Defense if that's any help. If anyone can remember this game I will be forever in your debt. Thanks in advance!