Going up the spine
When you get to the zigzag path structure up to the control room, you can bypass the path by instead walking up the central spine that starts way back out in the snow. You can take out enemies from distance with a pistol or sniper rifle, or rocket launcher. At the place where the spine starts, there's a load of supplies in the crevice (a nice surprise when I eventually stumbled across it), and often one or more Elites who got trapped there with their Ghosts (not such a nice surprise).