One of the biggest obstacles to building a space elevator has always been the choice of material for the
tether. Until recently, there was no material known to man that could handle the stresses involved. With
the discovery of carbon nanotubes, the strongest material known to man, a possible solution has been found.
Carbon nanotubes are a current hot topic in research. They have been found to be the strongest material
known to man and to be electrically conductive. There is current research trying to use carbon nanotubes
in nanocomputing.
Carbon nanotubes come in two varieties: single-walled nanotubes and multi-walled nanotubes. Although the
multi-walled nanotubes are too heavy to be used in space elevators, there is research to find uses for them,
such as bullet proof vests.
The strength to weight ratio of single-walled nanotubes is incredible. According to the Wikipedia article on
carbon nanotubes:
Scientists working at the University of Texas at Dallas produced the current toughest material known
in mid-2003 by spinning fibers of single wall carbon nanotubes with polyvinyl alcohol. Beating the
previous contender, spider silk, by a factor of four, the fibers require 600J/g to break. In comparison,
the bullet-resistant fiber Kevlar is 27-33J/g.
The article also lists the highest observed tensile strenght of carbon nanotubes as being 63 GPa.
Carbon nanotubes are strong enough, but why are they still not yet feasible? Although small quantities of
single-walled nanotubes have been shown to be strong enough, it is still impossible to manufacture sufficient
quantities. Until efforts are put into developing ways to mass produce them, carbon nanotubes will be merely
a hypothetical building material. However, with many large corporations looking towards nanotubes as the next
big thing, it wouldn't be surprising to see high-volume production methods developed in the near future.
Carbon nanotubes certainly look promising for many applications, including a space elevator. Only
time will tell if it gets used for this application, but it is undoubtable that this interesting material
will be used for some sort of breakthrough technology.
Wikipedia is an excellent place to start for more information on carbon nanotubes.