[quote=@Dynamics]
Won't the enemy just swoop in and steal it as soon as we clear the challenges?
[/quote]

Vex: No. That I can guarantee. There's a reason we have to clear the challenges instead of simply busting into the structure. It's impossible to break in without incredibly specific calculations, calculations which they already had time to do for the entrance. We clear them out as we approach our goal, and we don't have to worry about Alliance being present to take it.