[X] Track down Vorselon's ship.
[ ] Defeat Vorselon's fighters.
See that big green thing in the distance? that's Vorselon's ship. Head towards it, and once you reach it, you'll encounter resistance in the form of enemy fighters. The ships will shoot at you, but you can shoot at their bullets to destroy them before they hit you. They will also drop pulse mines, which emit a pulse every 5 seconds or so that radiates from the mine, damaging your ship. Use R1 to fire your blasters and L1 to fire homing rockets. You need to kill off all 25 of the attack vessels to be able to land on Vorselon's ship.
Once all the ships have been destroyed, land on Vorselon's ship.