Portal:Space exploration/Featured/December 2006

A space elevator is a theoretical structure designed to transport material from a planet's surface into space. Many different types of space elevators have been proposed. They all share the goal of replacing rocket propulsion with the traversal of a fixed structure via a mechanism not unlike an elevator in order to move material into or beyond orbit. Space elevators have also sometimes been referred to as beanstalks, space bridges, space lifts, space ladders or orbital towers.

The most common proposal is a tether, usually in the form of a cable or ribbon, spanning from the surface to a point beyond geosynchronous orbit. As the planet rotates, the inertia at the end of the tether counteracts gravity and keeps the cable taut via centrifugal force. Vehicles can then climb the tether and escape the planet's gravity without the use of rocket propulsion. Such a structure could eventually permit delivery of great quantities of cargo and people to orbit, and with transportation costs of a fraction of the traditional methods of launching a payload into orbit.

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