From what I’ve read so far, a space elevator’s counterweight must extend beyond geostationary orbit in order to keep tension on the tether. If you’re higher than GEO, your orbital period will be longer than a day, so how is the counterweight kept stationary when it’s higher than GEO?
In: Physics
Space elevator is not a practical concept. It only works if you ignore a bunch of things that make it not work.
For an elevator off of an earth sized mass, rotating at earth speeds, you need an impossibly tall structure to reach a position in space that is at the point of a geosynchronous orbit. This structure can be counter balanced by making it twice as long.
We don’t have any materials that are capable of making the structure feasible.
One problem they usually ignore about space elevators is that our planet has an atmosphere, which will flow around the base of the elevator, putting forces on it, and the resulting drag needs to be compensated for.
Even less often mentioned is that the elevator will tend to wick atmosphere up, resulting in the gradual escape of air molecules which are then lost to space, and eventually the planet loses its atmosphere.
And another problem with the concept is that the elevator will slow the spin of the planet, as rotational velocity will be bled off as mass ascends the elevator. The more mass you send up, the further out, the more you slow down the planet’s rotation and lengthen the day. Put enough mass up there and the earth’s center of gravity moves and the whole planet starts to wobble. The effects of this will be tiny and slow, but over a long time scale are not negligible, and would be ruinous to life on the planet.
The space elevator concept might work better on smaller planets without any atmosphere, but then on such a body you probably don’t need an elevator since conventional lift rockets will also have an easier job to do and so will work better than on earth, making the advantages of the elevator less.
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