It is possible to make a tower which extends upwards from the surface of the Earth into space. An equation for the taper ratio of such a tower is calculated under the assumption that the taper is chosen so that stress in the material is independent of height. The mass of the tower will then depend on the height of the material chosen. For a structure extending all the way to geosynchronous orbit, the mass of a compression structure of the tower and the characteristic strength-to-density ratio (“tower”) is less than that of a tension structure (“skyhook”) for the same ratio of strength to density. A structure which connects a tension structure at high altitudes with a compression structure at low altitudes has lower mass than either a tension or compression structure alone. A mass of 3.5 million tons was calculated for such a structure sized to carry a payload of 22.8 tons, using graphite-epoxy construction. Towers of height less than geosynchronous orbit were also examined. A 2280 km tall tower was shown to be feasible with current materials technology, with a mass of only 365 tons.
Journal of the British Interplanetary Society
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