Your weapons officer can target missiles fired by Torgoth vessels. Select them like a normal target and your primary beams will fire and destroy them if the missile is within your beam arcs. Blast weapons detonating near by can also destroy the missiles, however the missile itself will not detonate a blast weapon (mines or nukes) as I recall. If you do not destroy them, they will continue to follow you forever; they are relentless! I can't recall whether they are vulnerable to the gravitational effects of blackholes.