The technology problem holding back space elevators

Curious creatures, humans. People have imagined ascending to the heavens where riches await probably for as long as they have looked up in wonder at the glittering stars. It’s a belief common to many faiths and fairy tales, including Jack and the Beanstalk, first printed in 1807. Jack climbs up to a land in the sky and, to cut a short story shorter, finds a fortune to set him up for life.

Then the scientists got involved. In 1895 Konstantin Tsiolkovsky published his concept for a space elevator that would carry objects to a height of 35,790 kilometres at sufficient velocity to be launched off the top into geostationary orbit at that height.

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“One problem is that carbon nanotubes are the only known substance considered strong enough to support such a structure, but no-one has yet managed to build a strand of them longer than one metre. So for now, the idea makes about as much sense as Led Zeppelin’s 1971 Stairway to Heaven song lyrics. Which is to say, not much sense at all”

Still, it makes you wonder.
It really makes you wonder.

The Rev Dodgson said:

“One problem is that carbon nanotubes are the only known substance considered strong enough to support such a structure, but no-one has yet managed to build a strand of them longer than one metre. So for now, the idea makes about as much sense as Led Zeppelin’s 1971 Stairway to Heaven song lyrics. Which is to say, not much sense at all”

Still, it makes you wonder.
It really makes you wonder.

Mostly about what that sound is in my hedge. Kinda sounds like a couple of hippies going for it to tell the truth. What with all the “wow farout“s and “that’s so groovy“s.

> “One problem is that carbon nanotubes are the only known substance considered strong enough to support such a structure, but no-one has yet managed to build a strand of them longer than one metre”

Only a few years ago that was two centimetres.

Work on nanotubes at CSIRO has focussed on weaving them into a strong thread. When nanotubes were only 0.5 centimetres long this was impossible – a “strong” thread had only about 1000th of the strength of the sum of strengths of the individual fibres. At two centimetres long it was barely possible, because the bonds between one nanotube and the next are very weak. Now that nanotubes have reached one metre long, with the process of weaving them together to make a strong ribbon is almost trivially easy to make a thread that is nearly as strong as the sum of the strengths of each component nanotube. I told the CSIRO workers this.

Now the only remaining problem is mass production.

mollwollfumble said:

> “One problem is that carbon nanotubes are the only known substance considered strong enough to support such a structure, but no-one has yet managed to build a strand of them longer than one metre”

Only a few years ago that was two centimetres.

Work on nanotubes at CSIRO has focussed on weaving them into a strong thread. When nanotubes were only 0.5 centimetres long this was impossible – a “strong” thread had only about 1000th of the strength of the sum of strengths of the individual fibres. At two centimetres long it was barely possible, because the bonds between one nanotube and the next are very weak. Now that nanotubes have reached one metre long, with the process of weaving them together to make a strong ribbon is almost trivially easy to make a thread that is nearly as strong as the sum of the strengths of each component nanotube. I told the CSIRO workers this.

Now the only remaining problem is mass production.

Yeah a bit of wool is only about 30 cm long. Cotton would be less.

don’t natural fibres have a roughness that allows them to grip each other? do carbon nanotubes possess this feature?

Would a carbon nanotube woven cable that extends into the upper atmosphere or beyond provide a stable path for seperation of charge to equilibrate? ie; would you be grounding out the earth’s magnetosphere?

seeing that the magnetosphere originates inside the earth then i guess not.

ChrispenEvan said:

seeing that the magnetosphere originates inside the earth then i guess not.

but there is a different charge dispersal at the ionosphere than at the surface.

is there? reference please.

also it’s magnetic so how would you earth a magnet?

ChrispenEvan said:

is there? reference please.

http://en.wikipedia.org/wiki/Earth’s_magnetic_field

“A map of intensity contours is called an isodynamic chart. As the 2010 World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.”

If you extended a cable from an equatorial position to an altitude that entered the earth’s magnetic banding wouldn’t this present a shorter route to ground for the accelerated particles in the magentosphere?

Postpocelipse said:

ChrispenEvan said:

is there? reference please.

http://en.wikipedia.org/wiki/Earth’s_magnetic_field

“A map of intensity contours is called an isodynamic chart. As the 2010 World Magnetic Model shows, the intensity tends to decrease from the poles to the equator. A minimum intensity occurs over South America while there are maxima over northern Canada, Siberia, and the coast of Antarctica south of Australia.”

If you extended a cable from an equatorial position to an altitude that entered the earth’s magnetic banding wouldn’t this present a shorter route to ground for the accelerated particles in the magentosphere?

An explanation to the answer to this question is conspiciously absent. If a nanotube cable was extend from the equator to the limits of the earth’s magnetic banding, why would this not create a charge separation that would allow a high current to flow through the cable?

ChrispenEvan said:

don’t natural fibres have a roughness that allows them to grip each other? do carbon nanotubes possess this feature?

Excellent question. I happen to know the answer. Pure carbon nanotubes slide over one another as easily as graphene sheets in graphite. However, it is now possible to buy carbon nanotubes of the shelf that have been chemically treated to increase that grip.

mollwollfumble said:

ChrispenEvan said:

don’t natural fibres have a roughness that allows them to grip each other? do carbon nanotubes possess this feature?

Excellent question. I happen to know the answer. Pure carbon nanotubes slide over one another as easily as graphene sheets in graphite. However, it is now possible to buy carbon nanotubes of the shelf that have been chemically treated to increase that grip.

So does that mean we can now put this stuff in our 3D printers and print some carbon nanotube rope?

mollwollfumble said:

ChrispenEvan said:

don’t natural fibres have a roughness that allows them to grip each other? do carbon nanotubes possess this feature?

Excellent question. I happen to know the answer. Pure carbon nanotubes slide over one another as easily as graphene sheets in graphite. However, it is now possible to buy carbon nanotubes of the shelf that have been chemically treated to increase that grip.

or use nano buds for a mechanical lock.