There are several problems facing those who might build a
space elevator.
Where to Anchor a Space Elevator?
First, one has to find a place near or at the equator that
is both geologically and politically stable. There are very few if any such
places on the land. One solution may be to anchor the space elevator on an
offshore platform, in the middle of the ocean. Weather is generally calm at the
equator and such a station could be made accessible by ship or aircraft.
What Material to Build a Space Elevator From?
When the space elevator was first proposed over thirty years
ago, no material then in existence was strong enough to withstand the tensions
which would be required for a structure stretching from the Earth to
geostationary orbit. Recently, a material called carbon nanotube has been
developed that might fill the bill. Discovered in 1991, carbon nanotubes have a
tensile strength that is over fifty times that of steel but of much lighter weight. In certain
configurations it can either conduct or insulate electricity. It is many times
thinner than a human hair. It is being considered for a wide variety of
applications besides as a building material for space elevators. So far it has
not been produced in quantity, but researchers are confident that problem can
be solved in the near future.
What about meteors and other hazards?
One threat to a space elevator would be orbiting space
debris such meteors or space junk. A space elevator can be designed to
withstand micrometeor strikes that have occasionally pitted space craft such as
the shuttle. For larger hazards, the space elevator will have to be designed to
avoid them by moving the anchor platform and thus the elevator.
Of course a space elevator would be a prime target for a
terrorist attack. Measures would have to be taken, including setting up no fly
and no sail zones around the anchor platform, which would be in a remote location, and otherwise defending the
elevator.
How Much Will it Cost?
Most researchers think that the first space elevator could
be built at a cost of ten to fifteen billion dollars. Initially, it would cost
a hundred dollars a pound to send something into space on a space elevator, but
sharply decreasing as capacity and volume are added.