A Space Shuttle can put about 24 metric tons (53,000 pounds) in a low orbit, so at least the equivalent of four shuttle launches and some in-orbit assembly would be required to put a complete deployer in space. The tether deployer satellite will be rather large and heavy in Edwards's estimation over 80 metric tons (175,000 pounds) in mass, including propellant to move it from a low Earth orbit to GEO. Kennedy on a cable with a diameter of just under 10 cm (4 inches)! In comparison, the tensile strength of steel is only 42,000 kilogram per square centimeter (93,000 pound per square inch), or just over 3 percent of what would be needed for a space elevator (for more on this topic, see Cable Material in Chapter 7). Using a cable with such an incredible tensile strength, it would be possible to vertically suspend the entire, fully loaded, 83,000 metric ton (183,000,000 pounds) aircraft carrier U.S.S. Edwards is confident that the ongoing development of nanotube materials will eventually result in the tensile strength, with a safety factor of two, of 130 gigapascals that he needs for his design 130 gigapascals translates to a load of 1,300,000 kilogram per square centimeter (18,500,000 pounds per square inch). The use of anything else would result in an extremely heavy and thick cable, requiring thousands of rocket launches to put up. The ribbon will likely be based on strings of carbon nanotubes held together by an epoxy matrix. This tether would have to be made of a revolutionary, extremely strong, and not-yet-existing material. In his plan, construction begins with the launch of a satellite carrying a spool of ribbon tether, paper-thin and tapered from about a third of a meter (one foot) wide at GEO to some 14 cm (5 inches) at Earth's surface. Working on NASA grants (a total of $570,000 by 2003) and leading a research staff of 70 people at the Institute for Scientific Research (ISR) in West Virginia, he has developed a more refined strategy. However, important improvements have recently been proposed by Bradley Edwards, a pioneer in the field of space elevator engineering.
The idea of starting the construction of a space elevator from geostationary orbit, as proposed in I960 by Yuri Artsutanov, is still the baseline for current space elevator plans.
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