A space elevator is a theoretical idea for a type of space transportation system. First proposed many years ago, it has just recently been put up for more consideration by the United States and Japan. An elevator that is capable of reaching space from Earth would consist of a cable fixed to the Earth's equator, reaching into space. With an attached counterweight at the end, the center of mass is kept well above the level of geostationary orbit. Upward centrifugal force from the Earth's rotation enables the cable to remain tightly drawn, fully countering the downward gravitational pull. Once above the geostationary level, climbers would have weight in the upward direction as the centrifugal force overpowers gravity.
The stuff of a Hollywood movie?
It might be the stuff of a Hollywood movie when you hear about an elevator that can reach into space, but a Japanese construction company has announced that it intends to build a working space elevator and complete it by 2050. The Daily Yomiuri stated that the construction company Obayashi Corp will build a space elevator that is capable of shuttling passengers 36,000 kilometers above the Earth's surface by 2050. Using cables made from carbon nanontubes, which are 20 times stronger than steel, will connect to the terminal station 36,000 kilometers above Earth. Cars riding along the cable will carry 30 people and travel at 200 kilometers per hour. An Obayashi official stated that they cannot estimate the cost for the project. However, they are trying to make steady progress so that it won't end up as simply a "dream."
The idea of a space elevator surfaced in 1895 by the Russian scientist and school teacher Konstantin Tsiolkovsky. Inspired by a view of the Eiffel Tower in Paris, Tsiolkovsky conceived of the idea to consider a tower that would reach all the way into space, built from the ground up to the altitude of geostationary orbit. The tower would be built from the ground to an altitude of 35,800 kilometers.
He stated that a "celestial castle" at the top of a spindle-shaped cable would have the "castle" orbiting Earth in a geostationary orbit so that the castle would remain over the same spot on Earth's surface. Unlike recent concepts for space elevators, Tsiolkovsky's theotertical idea of a tower was a compression structure, rather than a tension, or "tether", structure.
Konstantin Tsiolkovsky was born on September 17, 1857, in the Ryazan Province south of Moscow. He was the fifth born child out of 18 children in his family. A near complete loss of hearing in his childhood left Tsiolkovsky impaired for the remaining years of his life and most historians will agree that his disability helped to stimulate his desire for book reading and focused him on his inovative ideas, including the idea for his "celestial castle."
Will it ever be possible?
Due to Earths' strong gravity, current technology is not capable of manufacturing tether materials that are strong and light enough to build a space elevator. However, recent concepts for a space elevator design are worth noting for their plans to use carbon nanotube or boron nitride nanotube based materials as the elastic element in the tether design. The strength of these molecules is high compared to their densities, and they offer promise for the possibility of making the first Earth-based space elevator.
An alternate lift system may also be applicable to other parts of the universe for planet-to-planet transportation. For locations in our solar system where there is a weaker gravitional system than Earth's, the strength requirements won't be as great for tether materials. Currently, there are materials available such as Kevlar that are strong and light enough that it might be considered as a material used for the tether.