We knew that a rocket was about to take off from Dusty Depot, but we didn't know the exact date. For several hours now, the takeoff countdown has been visible on the launch site.
It indicates a specific time at which the event called "The End" will take place, ending Season 10 of Fortnite. It's on Sunday, October 13 at 2PM EST that the rocket will take off — or something important related to it.
For the moment, we don't know the content of this mysterious end-of-season event. Built by the Scientist for a purpose that remains unknown today, the rocket will of course have a significant role in his plan. Some dataminers — such as Asriel_dev — predict a kind of big bang, during which all players and set elements will be sucked in and spit out on a brand new map.
These are just theories and Epic has not yet confirmed anything.