If it was that easy I would have them done by now. I have like one friend to finish the Thorn mission with and we failed the first time and he hasn't been on to run it a second time. The second one requires me to dismantle 10 rare or higher fusion rifles and there's really nothing I can do about that. I could farm and pray I get blue special engrams that contain fusion rifles or just casually play the story missions. The last exotic bounty I don't know. I haven't even picked one yet since these other two aren't complete.