Posted on 10/23/2006 7:19:57 PM PDT by KevinDavis
The idea of an elevator or transportation infrastructure to space has captured the imagination of scientists and writers around the world- Dr SS Verma In simple terms the difference between supernatural powers described in mythological scripts and science & technology is that the later makes things/benefits available to common man easily whereas the former one are limited to the people bestowed with supernatural powers or to those to whom they would like to oblige. Space exploration enthusiasm is growing not only with the planners to extract natural wealth from planets and natural satellites but also with common people in order to explore the space world experiences on their own. Like the availability of land, water and air movement resources for general public space exploration enthusiasm is also sweeping a new wave.
Presently available technologies of space exploration are proving to be very expensive, time consuming and thus limited for the use in specific purposes only. Scientists and technologists are thus, envisaging the development of space elevator technology to make space elevator a reality which will help every space travelling enthusiast to explore space economically and without wasting much time along with a. possibility to transport material from a planet's /natural sattalite's surface into space. Many different types of space elevators have been proposed sharing a common goal of replacing rocket propulsion with the traversal of a fixed structure. Space elevators have also sometimes been referred to as beanstalks, space bridges, space lifts, space ladders or orbital towers.
For more than a century, mankind has envisioned building an elevator to space. The idea of an elevator or transportation infrastructure to space has captured the imagination of scientists and writers around the world. New technological discoveries of the past decade - most notably carbon nanotubes - have brought the space elevator dramatically closer to reality. Combined with the recent completion of key NASA-funded feasibility studies on the project, the concept of the space elevator moves from the arena of esoteric research to commercial development and many companies are encouraged to start development work on the technology needed to create a space elevator.
There have been many differing opinions on the best way to build an elevator to space and there are several key milestones worth reviewing. There are a variety of tether designs. Almost every design includes a base station, a cable, climbers, and a counterweight. 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 keeps the cable taut via centrifugal force. Vehicles can then climb the tether and escape the planet's gravity without the use of rocket propulsion. Such a structure could eventually permit delivery of great quantities of cargo and people to orbit, and with transportation costs of a fraction of the traditional methods of launching a payload into orbit. As an alternative, a rotating skyhook placed in orbit of the earth, with spokes that touch down on the earth as it rotated is also being thought but even this skyhook is also too massive to be feasible. Building a cluster of cables made of carbon fibers, and then building a tower around the cables in which the cable would be anchored to a counterweight above geosynchronous orbit is also investigated. A proposal for an elevator consisting of a cable attached to an asteroid was also put forth in several scientific journals. One critical drawback to this proposal is actually harnessing and then managing the asteroid. The other is the proposed size of the cable itself.
The development and suitability of cable material is under way and after the cable using newly discovered graphite whiskers, running in both directions, from earth to space and space to earth from a satellite the discovery of carbon nanotubes has made the project of space elevator to move towards reality. Discovered in 1991, carbon nanotubes have the potential to be 100 times stronger than steel. Mixed with polymers to create carbon nanotube composites, carbon nanotubes are the only known substance at present that can successfully be used to create the ribbon needed to build an elevator to space. In the report on the studies, the space elevator consisted of a carbon nanotube ribbon some nearly 30,000 miles long and only a few centimeters wide. The ribbon would be anchored between a weight on earth and counterweight in space.
Though, orbital tethers are the only space elevator concept that is the subject of active research and commercial interest in space. However, there are other related concepts worth mentioning: a space fountain and a very tall compressive structure (i.e. a structure that stands on its own). A space fountain would use pellets fired up from the ground by a mass driver, the pellets traveling through the center of a tower. These pellets would impart their kinetic energy to the tower structure via electromagnetic drag as they traveled up and again as their direction was reversed by a magnetic field at the top. Thus the structure would not be supported by the compressive strength of its materials, and could be hundreds of kilometers high. Unlike tethered space elevators (which have to be placed near the equator), a space fountain could be located at any latitude. Space fountains would require a continuous supply of power to remain aloft. A space elevator could also be constructed on some of the other planets, asteroids and moons. A tether could be shorter or longer than one on the Earth but due to large difference in the surafce gravity and rotation times it will be easier to overcome the force of gravity of such planets/moons to launch into space.
Though there are still many areas related to space elevator to be investigated and verified/tested for the safety of climbers but with the completion of key studies, the space elevator is now progressing from the research lab into serious commercial development. It is in the phase to set up and build the space elevator. Under the plan, the space elevator will be operational in 15 years time. While experts concur on the possibility of building a space elevator, one might wonder what benefit might be to building such a transportation infrastructure to space other than human space travel. In general, experts agree that building such a structure would be of enormous economic and humanitarian benefits. Currently, the cost of launching a space shuttle is so high partly due to the amount of fuel it must carry in order to propel itself into space. Using beam or solar power to remotely fuel space elevators could be the key to eventually allow scientists to transport equipment into orbit, some 36,000 kilometers from earth, at much lower cost.
A functional space elevator can open up many markets and applications. Energy is one area that could benefit from a space elevator. Large solar arrays, for example, could be easily lifted into space, creating an inexpensive source of clean, limitless and eco-friendly energy, beamed back down to earth. Pharmaceutical research could also benefit, as centrifuges would not be limited by gravity as they are on earth. The result would be greater purity of chemicals. The same is true of crystals for electronics formed in space. Ultimately, the space elevator could be used for people to travel into space, from the moon, to Mars, and beyond.
Jehovah's Witnesses in space?
Have they somehow gotten around the few misaligned atoms which would greatly reduce the strength of a carbon-nanotube cable for a space elevator?
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