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SPACE_ELEVATOR

                                                        March 21, 2018

A simple form of the space elevator idea
would be a car that rides up a cable that
goes all the way up to a geostationary
orbital base.  The cable might actually
continue on up to provide a
counter-weight.  If you have two-way          So, this is a heavy up-front
traffic the energy of cars moving down        investment that's intended
can power the cars moving up.                 to reduce energy expenditures--
                                              but it's worth remembering
                                              that the *energy* to get to
                                              earth orbit isn't really
                                              prohibitive (I've heard it
                                              compared to flying across
                                              the United States.)

An object in geostationary orbit is
literally stationary with respect to
the ground (at higher orbits the
orbital velocity is slower, at lower
orbits, it's faster).  These are
sometimes called Clark orbits, after
the SF writer who observed that they
could be used for communication
satellites-- in these orbits they'd
behave like the the tip of an
incredibly tall radio tower.

But these towers can only be built at the
equator, which is the natural location for
a basic space elevator.

The cable for an earth based space elevator
remains a nasty strength-of-materials
problem, though-- it's often suggested
that they're more practical for lower
gravity bodies like mars or luna.



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