Re: shuttle disaster (space elevators)
Paul E Condon writes:
> It is not hard to compute the tension in a space elevator ribbon. (It
> would be a fair question for a final exam in an undergraduate mechanics
> course.) It depends on position along the ribbon, on the Earth
> parameters (size, rate of rotation, etc. )...
In particular there is no reason for there to be any significant tension is
the cable at the base. With proper controls such a cable should just hang
there if severed at or near ground level. A fail-safe design would make
the connection to the bottom anchor the weakest point so that an
over-tension event would not result in a cable fall. The real risk comes
from an impact high up on the cable.
> ...the mass-per-unit-length (kg/m) that is assumed for the ribbon.
Which must be tapered, of course.
> The last time I checked, there was not a material having a suitable
> combintation of kg/m and tensile strength.
Theoretically any material will work, but the dimensions get out of hand
when using wet spaghetti. In practice carbon nanotubes are strong enough.
--
John Hasler
john@dhh.gt.org
Dancing Horse Hill
Elmwood, Wisconsin
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