This idea dates back many years and some serious articles have been written on the topic, an elevator structure, or perhaps a cable, that would span the distance from the surface of the earth into space. There is one issue about this that has long bothered me. How would such a thing cope with the earth-to-ionosphere capacitance?
Please consider the following sketch:
There are two natural structures to deal with, the planet itself and the planet's surrounding ionosphere, each of which serves as one plate of a multi-thousand mile large capacitor.
I once read that this earth-to-ionosphere capacitance may be charged to 100 kV. (The writer of that item didn't specify the polarity.) If we now propose to put in place a man-made structure that will span the distance between those two capacitor plates, that structure would bridge the earth-to-ionosphere capacitance and that 100 kV.
How would it be possible to prevent that span from electrically discharging that capacitance, thereby inducing heaven only knows what ecological consequences?
There was a Star Trek Enterprise episode where Tuvok and Neelix were riding in a Space Elevator such as this and the apparatus all worked, but what about in real life?
Personally, I would only start to worry about such conduction if-and-when we find a material capable of supporting its own weight through an equivalent 23,000 km drop.
Even then, I doubt conduction would be a major issue (in spite of the high sheet conductivity of the ionosphere), as space-charge and other electromagnetic effects mean that the potential already varies considerably across the planet.
If it were an issue, it would merely be a design constraint - either on the cable conductivity or on the thickness of covering insulation.
Posted by: George Storm | November 18, 2012 at 09:14 AM