Once you land on planet Gaspar, Turn 180 degrees from where you start and go to the edge of the cliff and you'll notice a path. Go down this and you'll notice several little islands that you can jump between. Now you should be seeing large metal islands with ships tethered to them. It's these ships you need to blow up.
To destroy them, simply destroy the pumps at the base of the fuel pipes linked up to the ships. If you end up missing one, it should be easy to spot and then get to.