How efficient is iron smelting ?
With our current and near future technollogy (excluding the millitary industrial complex) wouldnt it be a easier to mine from Saturns rings? Are there any good guesses out there as to what those rings are composed of? If an asteroid could be identified as rich in one particular mineral, with a probe. Send something to push it out of the belt, and back to earth orbit. That way you arent sending a facility all the way out there to contend with all that debris pelting and etching away at your hull, and navigating through the bigger stuff. Hell, use some of the old nuke rockets. Send a whole battery of them out there, because chances are. It could take a few attempts to get it to the ateroid are targeting. Could use the nukes to clear a path, and the boosters "no relation" to attach and push it out of the area. Then bring in a more sophisticated ship to attach and bring it back to earth orbit.
I guess my way of thinking is, use what you allready have. Im sure theres lots of surplus millitary shit that could be used in such an endeavor.