Is a space elevator worth its weight in diamonds?
In 1975, Jerome Pearson wrote a great paper on space elevators that became the basis for excellent work by Brad Edwards including his 2002 book with Eric Westling, The Space Elevator: A Revolutionary Earth-to-Space Transportation System. For decades elevator enthusiasts have had their hopes pinned on carbon nanotubes or “graphite whiskers” as they were called in Pearson’s era. Pearson had a chart (Figure 2 on p. 789) indicating that diamonds have a “characteristic height” of over 3,000 kilometers for space elevator construction. This suggests that a 3,000-kilometer untapered diamond cable can support its own weight hanging at 1g. Pearson calculated that integrating the lower gravity along the cable to geosynchronous orbit results in a cable that is strong enough to hold its own weight from only “4900 km high in a uniform one-g field”. That suggests that a taper ratio of three would be conservative with the maximum cross section at synchronous altitude.
