Bungie’s Destiny will have its servers undergoing maintenance later today at 7:30 AM PT for two hours. Players won’t be able to log in at that time and by 8 AM PT, you’ll be kicked out of any activity you’re currently in since servers will go down.
Maintenance will complete by 9:30 AM PT with access to Bungie.net and the companion app “restricted” at that time. In-game messages will be sent to players warning them of the maintenance so you’ll have enough time to finish things up before logging out (or at least ensure you don’t wipe on that next round of Oryx).
Destiny’s Rise of Iron is out on September 20th at 2:30 AM PST and all this maintenance is usually done by Bungie in preparation for major changes and an excess of players coming in for the expansion. It’s also possible that something new is added today. Perhaps PvE content like Fallen Splicers running about? Stay tuned for more information later today.