Fabio Pacucci on the Science of Space Elevators

This short video comes from the TedEd channel on YouTube, presumably connected to the TED talks in which leading intellectuals and academics explain their ideas. In this case, its about space elevators. These are long cables that would carry materials and passengers up to Earth orbit. The idea was first proposed by Russian space pioneer, Konstantin Tsiolkovsky, in 1895, after the deaf school teacher saw the tallest building in the world at the time. If one could be built, it would massively reduce the costs of transporting people and material to orbit. These would be taken aloft in special capsules called ‘Climbers’, which would have to be shielded against radiation to protect human passengers. At the moment, it costs SpaceX $7,600 per kilo. It’s estimated that space elevators, their immense power needs supplied either by solar energy or nuclear power, could reduce this by 95 per cent. The problem is that that at the moment there is no material strong enough to support such a building. It has been suggested that carbon monofilaments and nanotubes could provide the solution, but only tiny amounts of these have been manufactured at the moment. There is also the problem that the gravitational stresses and hence the thickness of the cable would vary with height. One solution to this problem would be to extend the cable to counterweight, either a satellite or captured asteroid in geostationary orbit 36,000 km above the Earth. The problem of keeping the tether rigid would be solved by using centrifugal force from the Earth’s spin. The station back on Terra would be best situated at the equator, and possibly a ship at sea. This would allow it mobility to avoid storms and terrible weather. It is immensely difficult to build such an elevator on Earth, but they could be built on the Moon and Mars using current technology and materials. But they’d be far more of an advantage built here on Earth. Another problem is that if the cable was cut, the effects as it fell to Earth would be catastrophic. Despite the difficulties of construction, there are companies in China and Japan planning to build them by 2050.

The idea of the space elevator has been around for some time. Arthur C. Clarke thought for a while that he had invented the idea in his book about the building of such a tower in his adopted home of Sri Lanka in his 1970s novel, The Fountains of Paradise. This lasted until he looked the idea up in the scientific literature, and found it went all the back to the Russians. It would truly be a giant leap in space exploitation and colonisation if we could build a space elevator, but I think building one by 2050 is extremely optimistic. Way back in the 1990s or the early part of this century I remember an American firm announcing they were going to develop the idea. Unfortunately one of the problems at the time is that, according to the techniques being proposed, the station back on Earth would have to be anchored by an entire mountain range. So, not really possible and that was the end anyone heard of the idea.

It’s great that research into space elevators is continuing, but I think it will be a long time before they become reality, whether built by Americans, Chinese, Japanese or whoever.

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One Response to “Fabio Pacucci on the Science of Space Elevators”

  1. Ben Oldfield Says:

    A more practical transport system to space would use a linear motor driven system driving capsules into space. To minimise power requirements a very high mountain or plateau close to the equator would be required.

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