Space Elevators: How Do They Work?
By Andy Darnley
The concept of a space elevator might seem like something out of a science fiction plot. However, scientists have been considering ideas to make this concept a reality for hundreds of years. In 1895, a Russian scientist named Konstantin Tsiolkovsky studied the Eiffel Tower and had some new ideas. This Parisian structure gave him the idea of a tower stretching up into space from the ground. Some parts of Tsiolkovsky’s idea were rudimentary, but the basic concept has continued to inspire scientists.
New ideas have surfaced in the past 100 years with suggestions for the material needed for the elevator cable and the use of a counterweight to help deal with gravity and centrifugal forces. In 1979, Arthur C. Clarke wrote the book The Fountains of Paradise, and this novel chronicled the construction of a space elevator on a mountaintop. Other books followed Clarke’s novel that also included space elevators in their plots. With the creation of strong carbon nanotubes during the 1990s, scientists began wondering if space elevators were actually possible.
Competitions have taken place to motivate the development and design of space elevators. One company, the LiftPort Group, even made a formal announcement of its plan to begin building the materials necessary to develop a space elevator. Unfortunately, this company later went out of business.
Why Do Scientists Want to Build a Space Elevator?
Exploring space has a strong pull for scientists. However, a number of limitations have made space exploration challenging. Launching astronauts into space via rockets is very expensive. Rockets are also inherently unfriendly to the environment. Carbon emissions from rockets have been flagged as having a potential impact on climate change. In contrast, a space elevator could lift people and items into space less expensively, more safely, and with less negative impact on the environment.
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How Will it Work?
A space elevator would involve a tether anchored to the ground and stretching up into space. At the top of the elevator, a counterweight will serve to keep the cable taut. Centrifugal force will actually be responsible for holding the tether in space as the Earth rotates slowly. Centrifugal force will help keep the tether aligned and stretched in a taut position. However, the placement of the tether on the ground will be an important element because centrifugal force varies in strength depending on position in relation to the Earth. Cars or climbers will attach to the tether, and a source of power will move them up and down.
Devising a means of powering the climbers has been a challenge because most sources of power would add too much weight to the cars. A possible technique for powering the climbers involves shining a beam of light up from the ground, which could be converted into electricity. The climbers would move more slowly than a rocket. However, the benefit of this transportation method is that it would be smoother without the harsh g-forces and explosives propelling the climbers into space.
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Can it Be Done?
While many scientists are excited about the possibility of a space elevator, others are pessimistic about the success of such a project. The sheer length of the cable is a major challenge in this project. Scientists estimate that the cable would need to be about 22,000 miles long for it to extend into geosynchronous orbit. Extending into geosynchronous orbit would be necessary to ensure that the counterweight matches the Earth’s rotation speed. The strength of the cable is another problem that continues to vex scientists. Using carbon nanotubes sounds plausible, but scientists have not yet figured out how to build a structure at the required length out of carbon nanotubes.
Another concern is the potential for unpredictable vibrations that could occur from solar winds. These gusts could make the space elevator unstable and dangerous. Current technology has not enabled scientists to resolve these potentially serious problems. However, with continued research and development of new technology, a space elevator might be possible in the future.
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