The Raid challenge modes are all unlocked and Court of Oryx bosses are on rotation, making it possible to get those missing calcified fragments. HOWEVER: It is not possible to get the Gift Mast calcified fragment with the nightfall this week. Bungie, please change the nightfall strike to something on the Dreadnaught. Put whatever buffs you want on it, but please make it possible to get the last calcified fragment challenge done. EDIT: Or at least give us the opportunity next weekly reset to get it