- last post: 01.01.0001 12:00 AM PDT
It's not the Ark, people.
It is a big structure like the one in the background of Quarantine Zone. Go play Quarantine Zone again; notice the big blue beam coming out of the structure, and the metal plates on the sides? The structure on the earth in the trailer looks like a Quarantine Zone structure that is just beginning to "hatch."
In halo 2, when the capital ship caused a slipsace rupture, it wiped out New Mombasa, and since the ground above the earth structure was probably weak due to some ancient Forerunner excavation, the slipspace rupture probably quaked the whole freaking place and revealed the giant quarantine hatch.
So maybe all those capital ships (in the trailer) are there to activate the quarantine zone on earth, to prevent The New Covenant Order (Brutes, Prophets, Drones, and Jackals) from even finding the Ark.
But honestly, that earth structure looks more like the QZ tower than an "Ark." This theory I constructed is based on that.