Beanstalks

A Beanstalk or 'space elevator' is a type of planet-to-space transportation system. The main component is a cable (also called a tether) anchored to the surface and extending into space. The design permits vehicles to travel along the cable from a planetary surface, such as the Earth's, directly into space or orbit, without the use of large rockets. An Earth-based space elevator consists of a cable with one end attached to the surface near the equator and the other end in space beyond geostationary orbit (35,786 km altitude). The competing forces of gravity, which is stronger at the lower end, and the outward/upward centrifugal force, which is stronger at the upper end, results in the cable being held up, under tension, and stationary over a single position on Earth. With the tether deployed, climbers can repeatedly climb the tether to space by mechanical means, releasing their cargo to orbit. Climbers can also descend the tether to return cargo to the surface from orbit.

The concept of a tower reaching geosynchronous orbit was first published in 1895 by Konstantin Tsiolkovsky. His proposal was for a free-standing tower reaching from the surface of Earth to the height of geostationary orbit. Like all buildings, Tsiolkovsky's structure would be under compression, supporting its weight from below. Since 1959, most ideas for space elevators have focused on purely tensile structures, with the weight of the system held up from above by centrifugal forces. In the tensile concepts, a space tether reaches from a large mass (the counterweight) beyond geostationary orbit to the ground. This structure is held in tension between Earth and the counterweight like an upside-down plumb bob.

To date this concept has been executed three times successfully:


 * The Boyoma Beanstalk, just outside Kisangani, AROC, operated by IKP on contract to Global Resources
 * The Sunda Kelapa Beanstalk, over the sunken island of Java, Indo-Pacific Dominion, operated by Saraswati, in partnership with PWFB
 * The Pichincha Beanstalk, near Quito, Andean League, operated by Liberty Interplanetary, serving Amanha, CGI and other clients

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