Designing a space elevator
Calvin Dean
The idea of a space elevator to outer space is not particularly original. The first idea came from a Russian scientist, Konstantin Tsiolkovsky, in 1895, a decade after the invention of the electric lift. In the Bible, on the other hand, the first low-tech idea is found in Genesis about the Tower of Babel. Research is currently underway on a working space lift that could reduce the cost of transport to space by 93%. Because it is a complicated design, the space elevator is not without its engineering challenges. Among the most difficult are: designing a cable with the right material properties, overcoming the forces acting on the space elevator and finding a way to avoid space debris.
How does a space elevator function?
The space elevator would be a base on Earth connected by a long cable to a counterweight in space. This would be possible because of centrifugal force. Centrifugal force is a force resulting from the inertia of the body. It acts on a body moving in a circular path and is directed away from the centre around which the body moves. Let us take the example of a ball swinging around a pole. At a certain velocity, the ball is held taught by the tension against the centre of movement, the pole. Therefore, the space elevator is based on the same concept, but on a larger scale. The base for the space elevator must be somewhere on the equator because it
aligns with geostationary orbits (an orbit with a period equal to the Earth's rotation period). The geostationary orbit is necessary because it must remain in a position above the Earth otherwise the base must move to keep the tether taught. To stay in a circular orbit, the centrifugal force will have to equal the gravitational force.
𝐺𝑚 𝑝 𝑚 𝑠 𝑟 2
2 𝑟 =
𝑚 𝑠 (𝜔 𝑠 )
Gravitational Force
Centrifugal Force
𝑚 𝑠 - Mass of Satellite 𝜔 𝑠 - Angular Velocity
𝑟 - Distance to the centre of the Earth
𝑚 𝑝 - Mass of the Planet
𝐺 - Gravitational Constant
We can now input the values for Earth:
6.6742×10 −11 ×5.9737 ×10 24 ×86164 2 4𝜋 2 3
𝑟= √
312
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