Space Elevator :-
“ Japan invests 9 billion dollars for the construction of the SPACE LIFT,
estimated to be completed by 2031.
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. 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.
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 ther 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 weightof the carriage which will run up and down its length. It alsoneeds to resist corrosion, weather and the extreme cold of the upper atmosphere.
Carbon nanotubes (C60) are the only material which have thepotential 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 2031.
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