"I suppose you are talking about carbon-nanotube cable? Problem is this stuff doesn't exist- it's unobtainium."

Well, your right for the time being. I'm not saying it could be built NOW. I'm just playing with the mechanics. The rate CNT material research is progressing, I doubt it will be unobtanium beyond another decade or so...

Besides, Carbon-nanotubes exist, but manufacturing the cable is still a hurdle. Lengths of 100,000km are probably over the forseeable horizon too. That's not necessary anyway. Shorter lenghts woven into a composite strip would give better durability anyway.

Your position on the issue is noted. If you have any constructive comments, please contribute.