Space Elevator

Currently the only way to get anything into space is by using rocket propelled vehicles, but whether they are single use vehicles or reusable craft like the shuttle, they are incredibly expensive to run and maintain.

However with the recent and continued development of carbon nanofibres (carbon nanofibres are immensely strong structures able to support incredible weights, while themselves weighing very little) there may be an alternative, albeit with its own drawbacks.

Space elevators are not a new concept, Arthur C. Clarke spoke of them in his novel '3001: The Final Odyssey'. But there have been some major engineering hurdles which have needed to be resolved before the concept can become a reality. And slowly technology is catching up with fiction.

A space elevator is a structure designed to lift cargo or personnel into orbit in much the same way a conventional elevator takes you to the top of a building. And although the initial cost of creating a space lift would be huge, in the billions of dollars, after completion the greatly reduced costs of getting heavy cargo into space would soon recoup the original investment.

Because of the vast sums of money required to build a space elevator, the project may have to be funded by a multinational governmental conglomeration, which creates many problems. Where to position the structure, who owns it, who controls it, and because space is militarised, what goes up there?

If however the project was to go ahead, and it is being researched, the most feasible space elevator proposal is a tether. A tether space elevator consists of several components. Firstly the base station.



The base station is the point at which the elevator is attached to the earth. Several proposals for the the base station have been suggested, including floating platforms which can be moved to avoid inclement weather and reduce the chance of damage, as well as land based stations, usually positioned at high altitude locations near the equator.

Artist Pat Rawling's depiction of a space elevator looking down on earth

To the base station is attached the tether. The tether is the cable which runs continuously from the earth to a geosyncronous orbital anchor point situated 21,700 miles (35,000 kilometers) above the earths surface. Possibly a captured asteroid or some other suitably large structure.
Obviously the tether is the section with the most developmental problems. The cable needs to be incredibly strong, able to support its own weight and the weight of the carriage which will run up and down its length. It also needs to resist corrosion, weather and the extreme cold of the upper atmosphere.
Carbon nanotubes (C60) are the only material which have the potential to cope with the desired stresses and strains of a space elevator. However the material needs further development and a reduction in manufacturing costs before it could be used in the quantities required for a tether. But its properties mean that it is currently the only viable option.

The vehicle, or carriage which travels up the cable has its own problems which need solutions before the space elevator can become reality. One of the biggest problems is the required energy necessary to climb all the way to the top. Because the cable is stationary, the carriage is required to crawl up its length. Several power systems have been proposed including nuclear power, regenerative braking (descending carriages pass their energy to ascending carriages), and laser or microwave power beams.
Whatever method prevails, it will power the carriage to crawl up the cable using roller wheels which grip the tether.

Obviously the exact science and technology behind any proposal for a space lift is baffling to all but the most cranially gifted. But the concept of an extraterrestrial elevator is one anyone can get excited about. And at the current rate of scientific advancement some experts have predicted that if it was desired, a working space lift could be operational by 2020.