Re: [math-fun] A modest proposal for carbon sequestration in space

=Henry Baker all of the proposals involve starting the elevator cable at the ground or some high tower

Actually, Hans Moravec's 1977 proposal ("A Non-Synchronous Orbital Skyhook" qv) *has* to start in the middle and grow in both directions, because it's not in geosynchronous orbit. This probably has both some advantages (better dynamics: thick in the middle, tapers toward the ends) and some disadvantages (ferrying up the building materials, rather than being able to use the cable as scaffolding).