Soooo long story short I was on destiny tracker and found something interesting[spoiler] although people have seen the letters before[/spoiler]
The letters just said letters from the vendors/important people
Now it's called The Dawning idk but when you go down to the speaker it says to commemorate The Dawning
http://db.destinytracker.com/items/consumables
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Look for the glowing pink symbol on the bottom of the pilar to your left when you spawn in the tower. That's probably gonna be the symbol of the event