The space elevator is a proposed non-rocket spacelaunch structure (a structure designed to transport material from Earth into space). Many elevator variants have been suggested, all of which involve travelling along a fixed structure instead of using rocket powered space launch. The concept most often refers to a cable that reaches from the surface of the Earth on or near the Equator to geostationary orbit (GSO) and a counter-mass outside of the atmosphere.
Discussion of a space elevator dates back to 1895 when Konstantin Tsiolkovsky proposed a free-standing "Tsiolkovsky" tower reaching from the surface of Earth to geostationary orbit. Most recent proposals focus on tethers reaching from geostationary orbit to the ground. The tethers would be held in tension between Earth and the counterweight in space like a guitar string held taut.
|Carbon nanotubes are one of the candidates for a cable material|
Recent conceptualizations for a space elevator are notable in their plans to use carbon nanotube based materials in the tether design, since the measured strength of microscopic carbon nanotubes appears great enough to make this possible. Technology as of 1978 could produce elevators for locations in the solar system with weaker gravitational fields, such as the Moon or Mars.
David Smitherman of NASA/Marshall's Advanced Projects Office has compiled plans for such an elevator that could turn science fiction into reality. His publication, Space Elevators: An Advanced Earth-Space Infrastructure for the New Millennium, is based on findings from a space infrastructure conference held at the Marshall Space Flight Center last year. The workshop included scientists and engineers from government and industry representing various fields such as structures, space tethers, materials, and Earth/space environments.
"This is no longer science fiction," said Smitherman. "We came out of the workshop saying, 'We may very well be able to do this.'"