After entering the final level inside the alien space station, you will see an impassable wall to the left. Fly your ship a little ways to the right and this will usually spawn a pterodactyl enemy. Lure the enemy back to the left, position your ship as close to the wall as possible, and kill yourself by colliding with the pterodactyl. When your next ship appears you will be on the opposite side of the wall and next to the final boss.