Obtainable Ringworld around the Earth?

On 1/5/07, Xenophile wrote:
(...)
> Well, I've got a simple solution to that, but it strays into
> unobtainium territory. Not by much, though.
>
> Since the ring is geostationary (despite being at Shuttle height), you
> could have a bunch of space elevators connecting it to the ground.
> Then, if one side drifts closer to Earth, the other side has to drift
> farther away, and the elevator ribbons won't allow that. You could
> position one, say, every thousand Km around the equator, giving you
> forty of them.
>
> And a tether that can support itself for 200 Km is probably more
> "obtainium" than one which can support itself for 35,792 Km.
(...)

Heck, why in hell I started to think about electrodynamic tethers when
there is a solution SO much simpler, and completely passive, like
yours!

I am not that good with materials science, but I guess that you don't
need any sort of unobtanium at all. AFAIR, some projects of rotovators
tens or even hundreds of kilometers long use polymers commercially
available now.