Black Mesa was an abandoned Missle factory. They had a few Apache helicopters there for defense reasons only. Black Mesa was favored my by the goverment more than Aperture Science. Sure Ap. Science Aperture had portal technology, but Black Mesa also had portal technology. So now you must be wounder, "Aperture science use to make shower curtains." or, "now that i'm almost down reading this, i will flame this guy and blurt out, Aperture science has a cool AI." In the end both science facilities were purged by the government in some way.