|N version||1.2 and later|
Method 1 (Easy)
A fairly open level, from the beginning run right and grab the door switch. Quickly jump back to the left before the rocket can approach, and then use the launchpad to get to the switch. To avoid an untimely death, hold right when going up the launchpad. The homing turret will see you to the right and fire in that direction; then hold left and you will fall into the exit switch ledge. The rocket will harmlessly crash against the wall.
Then, jump all the way to the right, using the slope to stop your fall. The bottom is a minefield guarded by a gauss turret (shake off any rocket that follows you). The mines are sparsely spaced so it isn't very difficult to make it to the exit.