Thu - October 2, 2003

Space Elevators v0.0.1


Space elevator origins, history, and generally where we stand now

The original concept for a space elevator was born of the mind of Konstantin Eduardovich Tsiolkovsky in 1895. The idea was inspired by the Eiffel Tower and consisted of a tower up to geosynchronous orbit 35,800 miles up. The idea languished until 1957 when Yuri N. Artsutanov added the innovation of lowering the cable from an orbiting satellite.

From that point, further significant development on the idea moves to the West. In 1966, the strength that a constant cross section cable would have to have was calculated by four American engineers. No existing material even had a theoretical strength capable of making such a cable. Things improved in 1975 when Jerome Pearson added the innovation that the cable should have a variable width along its length as different sections of the cable would come under different levels of stress.

Arthur C Clarke's Fountains of Paradise popularized the notion of a space elevator in the west. The problem remained, where are we going to find a material that is not only can hold its own weight, the weight of cargo, but also is tough enough to deal with the wear and tear of wind and collision with small objects?

In 1991, Sumio Iijima, working for NEC discovered the first serious candidate material, carbon nanotubes. These structures are the first, and so far only, material strong enough and light enough to at least theoretically create a space elevator cable. By 1999, enough people had connected the dots that NASA put on a conference examining the feasibility of a space elevator. The verdict was that it would be hard but was technically doable.

Today, carbon nanotubes are making huge strides. From a rare byproduct of a process designed to produce buckeyballs, carbon nanotubes today can be produced in bulk, can actually be spun to a visible length and the in the nanotube/epoxy resin composite that is the current favorite for the actual cable material, we're at 60% nanotubes with no clumping (90% being the final goal). There are a lot of basic problems left to be solved but instead of the pessimist's prediction of 300 years that came out of that '99 conference or even the optimistic prediction of 50 years, Liftport is projecting an April 2018 launch date. When they make it, a great deal changes. Lift costs range from $10,000-$40,000 per pound. A space elevator drops this to between $100-$200 per pound. All of a sudden a great many applications become practical at that point.

Posted at 02:05 PM    

©