I'm certain that everyone has seen the models for the tracked hog for artic warfare. I like the idea, personally, better traction on ice and snow, unlike the regular hog that was uncontrolable on the ice. It does make me think, however. Now, while on HALO 04 the snow was around the control room area... A debate for later. As for on Earth (if that is where it is being used) there are several places it might turn up. The first one that would normally come to mind would be Antartica or the north pole. Second would be Alaska or Wisconsin in winter. But knowing bungie and how they love conumdrums a third location came to mind.
Stick with me on this one, it is a little wild. Around 1900 or so (can someone find the exact date?) a unidentified object fell from space and exploded over a desolate part of Siberia (wait, that IS most of Siberia). Well, moving on, when people finaly were able to examine the site a few decades later they found that all the trees had been flatened in a odd figure eight like shape. The popular theroy is that whatever it was airbursted before it impacted, so there was no actual crater and the object was never found. Now here is the wild part, what is bungie is going to use that particular incident to explain the landing of a Forerunner artifact, like the MCPO Spartan 117 (MasterChief) recovered from the hunters in the Museum of Natural History. Like the other artifact, it contains the spacial coordinates for another of the Forerunner Halo Installations, and like the other installation, it has flood in containment cells, and possibly forerunners still alive and running the installation.