The physics of the space elevator

A space elevator is a tall tower rising from a point on the Earth’s equator to a height well above a geostationary orbit, where it terminates in a counterweight. Although the concept is more than a century old, it was only with the discovery of carbon nanotubes that it began to receive serious scientific attention. NASA commissioned a study of the space elevator in the late 1990s that examined the feasibility of such a structure and explored many of its applications. I explain the basic mechanical principles underlying the construction of a space elevator and discuss several of its applications: the transport of payload into space and the launching of spacecraft on voyages to other planets.