Space elevator
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A space elevator would consist of a cable [4] anchored to the
Earth's surface [6], reaching into
space. By attaching a counterweight [3] 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 [1]. Once beyond the gravitational midpoint [2], carriage [5] 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 as a way of
non-rocket spacelaunch. The term most often refers to a structure that reaches from the surface of the Earth to
geosynchronous orbit (GSO) and a counter-mass beyond. The concept of a structure reaching to geosynchronous orbit was first conceived by
Konstantin Tsiolkovsky,
[1] who proposed a compression structure, or "Tsiolkovsky tower." Most recent discussions focus on
tensile structures (
tethers) reaching from geosynchronous orbit to the ground. Space
elevators have also sometimes been referred to as
beanstalks,
space bridges,
space ladders,
skyhooks,
orbital towers, or
orbital elevators.
The most common proposal is a
tether, usually in the form of a
cable or
ribbon, spanning from the surface near the equator 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 reach orbit without the use of rocket propulsion. Such a structure could hypothetically permit delivery of
cargo and people to orbit at a fraction of the cost of launching payloads by rocket.
Current technology is not capable of manufacturing materials that are sufficiently strong and light enough to build an Earth based space elevator as the total mass of conventional materials needed to construct such a structure would be far too great. Recent proposals for a space elevator are notable in their plans to use
carbon nanotube-based materials as the tensile element in the tether design, since the theoretical strength of carbon nanotubes appears great enough to make this practical. Current technology may be able to support elevators in other locations in the solar system however, and other designs for space
