A laser-powered robotic climber travels up the ribbon adding additional nanotube fibers to strengthen it.

One of the problems inhibiting the development of a space elevator is that the steel cables commonly used for elevators are too heavy and not strong enough. In a tall building a major part of the weight that an elevator cable has to lift is that of the cable itself. Carbon nanotubes are Fullerene-like structures that are hundreds of times stronger than steel. One nanotube string about half the diameter of a pencil is able to support 20 full-size cars (40,000 kilograms). After their discovery in 1991 by electron microscopist Sumio Iijima, carbon nanotubes became the driving force essential to the space elevator's conception.

Carbon nanotubes are still extremely difficult to mass-produce. Current techniques, such as evaporating carbon rods or getting hot carbon gases to combine to form these molecular tubes still only produce small quantities, fine for work in a laboratory but not enough to make long ribbons. However, new breakthroughs in production technology promise to bring about rapid progress.

Building the Space Elevator: A satellite drops a nanotube ribbon toward earth. The elevator will climb up and down this cable.

To create the space elevator a satellite would be launched into a geostationary orbit 35,000 kilometers above the earth.

The satellite would then drop a nanotube ribbon towards earth while climbing into a higher orbit, eventually reaching an altitude of 100,000 km as the ribbon reached the earth's surface.

Robotic climbers powered by a laser beam aimed up from an earth station would travel up the ribbon adding more nanotube fibers to it for greater strength.

The ground station on the Earth's surface would be at an equatorial site with few storms. This would reduce the risk of lightning striking and damaging the nanotube ribbon.

	The ground station for the space elevator is a recycled offshore oil-drilling platform.

Once in place, the space elevator would provide a low-cost and gentle way of lifting people and cargo into space. As an added bonus the centrifugal force provided by the motion of the top of the elevator could help fling spacecraft to Mars and other planets.

There are, however, a number of challenges scientists are faced with to this day. The construction of composite nanotube structures still requires two to five more years of research before large scale production of nanotube ribbons is feasible. Space debris and micrometeors could puncture cables and lead to other catastrophes, yet researchers are confident that widening the cables at specific altitudes could overcome this problem. Then perhaps Mr. Edwards is correct; perhaps the space elevator will overcome all obstacles and be a revolutionary bridge linking Earth and Space. What a heavenly concept!

The space elevator images and movie in the article are © HighLift Systems and reproduced here with permission.

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