Space elevator

From Engineering

A space elevator would consist of a cable anchored to the Earth's surface, reaching into space. With the attaching of a counterweight at the end (or by further extending the cable for the same purpose), inertia ensures that the cable remains stretched taut, countering the gravitational pull on the lower sections, thus allowing the elevator to remain in geostationary orbit. Once beyond the gravitational midpoint, carriage would be accelerated further by the planet's rotation. Diagram not to scale.

A space elevator is a proposed megastructure designed to transport material from a celestial body's surface into space. Many different types of space elevators have been suggested. 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, skyhooks 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 also keeps the cable taut. Vehicles can then climb the tether and escape the planet's gravity without the use of rocket propulsion. Such a structure could theoretically permit delivery of cargo and people to orbit with transportation costs a fraction of those of more traditional methods of launching a payload into orbit.

Recent proposals for a space elevator are notable in their plans to incorporate carbon nanotubes into the tether design, thus providing a link between space exploration and nanotechnology.

[edit] External links

• Wikinomics Elevator to Space Article (claims to be based on the Wikipedia article, but is under a different license)

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