i have a un-turned in vanguard mentor missive from pre TTK drop. Every time I'm in orbit it shows a quest icon above the tower, and once there above Xander 99-40 (mission robot) the quest icon shows up, but when I approach him it shows no options to redeem the missive. Will there be new exotic quests coming and therefore a reason for me to keep the missive or is this something that will never have use again and I should just delete it?