Space elevator

A space elevator is a type of planet-to-space transportation system. The main component would be a cable (also called a tether) anchored to the surface and extending into space. The design would permit 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 would consist of a cable with one end attached to the surface near the equator and the other end in space beyond geostationary orbit. Possible materials used in the cable's construction are Carbon nanotubes (CNTs) or buckminsterfullerene. 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, would result in the cable being held up, under tension, and stationary over a single position on Earth. With the tether deployed, climbers could repeatedly climb the tether to space by mechanical means, releasing their cargo to orbit. Climbers could also descend the tether to return cargo to the surface from orbit. This could also be used as a launch-assist structure for a spacecraft.

Problems:

 * The cable will extend far beyond the orbit of most satellites, meaning that the orbits of satellites, after many passes around the earth, will eventually intersect the space elevator and cause a crash. Since satellites routinely travel at 18,000 miles per hour, an impact could be catastrophic. This means that the elevator has to be equipped with special rockets to move the cable out of the way of passing satellites.


 * Turbulent weather such as hurricanes, lightning storms, and high winds can be catastrophic. The space elevator must be anchored to the earth, perhaps on an aircraft carrier or oil platform sitting in the ocean, but it must be flexible to avoid being damaged by the powerful forces of nature.


 * There must also be a panic button and escape pod in case of a break in the cable. If something snaps the cable, the elevator cab must be able to glide or parachute back to the earth’s surface in order to save the passengers.

Economic benefit:
It is estimated that a space elevator will have a 95 percent cost advantage over orbital spaceflight and could potentially control all space activities near its planet. Construction would be hugely expensive but return on investment excellent.

Examples:
 * In 2061: Odyssey Three (novel by Arthur C. Clarke), the possibility of a space elevator is realized after a groundbreaking discovery that Jupiter's core had been a solid diamond; as the hardest substance in nature, suddenly available in vast quantities, it facilitates the construction of a solid elevator rather than the more common tether structure previously envisaged and in 3001: The Final Odyssey a ring habitat now exists around the Earth that is connected to the surface via four inhabitable towers (successors to space elevators)
 * The Fountains of Paradise (novel by Arthur C. Clarke) is about the construction of a space elevator on a mountain top on Earth in a fictionalized version of Sri Lanka.
 * The Long Mars (novel by Stephen Baxter and Terry Pratchett): In the parallel Martian worlds, the existence of the elevator is proven as to be a logical step for a long-gone civilization.
 * The Mars Trilogy by Kim Stanley Robinson depicts space elevators on Earth and on Mars, the cables of which are made of carbon nanotubes manufactured on asteroids and lowered into each planet's atmosphere, using the asteroid as a counterweight.
 * a space elevator in New Mombasa, Kenya in the year 2552 is seen in the Halo Universe
 * a space elevator is a World Wonder in Civilization