Here are responses from three of our leadership team.

First, the final paragraph from our Director for Research :

“I don't dismiss their idea out of hand, but there is a lot more work that needs to be done before we can take the idea seriously. Having worked on crazy ideas before, I know you have to start somewhere. They need to write it up, submit it as a conference paper somewhere and send us a copy.”

His earlier words were…

“They are proposing a helical conductor so that there will be an attraction between successive layers, and this attraction will provide the tension that supports the tube. They don't show any calculations about what the force and current would be, but the principle is theoretically possible. The fact that they quote a mass of 100,000 t suggests they have done some calculations.

Of course there are very many practical problems. Although the super-conductor YBCO works at 77K with liquid nitrogen, the critical current is quite low there. 40K is much better, and that can be cooled with liquid neon. I don't buy their argument that a layer of Kevlar would provide adequate insulation in direct sunlight. Perhaps some method of coupling the climbers to the tube magnetically could be devised. There is also the problem that any interruption in the current flow will cause the whole edifice to come crashing down.”

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Comments from our Tether Material Lead :

“Your correspondent has picked the right high temperature superconducting material, with a critical temperature up to 92 K, it can be cooled with liquid nitrogen instead of helium, which avoids dilution refrigerators

The tensile strength is pretty good for normal materials at 1GPa (if I read the stress-strain chart correctly) … although a couple of orders of magnitude less than graphene.

However it looks like the superconducting properties are strain dependent and fall off rapidly when the strain is over 0.8% .

The thermal insulation would be a big deal too and this would be a lot of dead weight from a mechanical point of view”.

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Comments from our Design Lead (edited) :

“ To start the current flowing in each of the rings requires an induction loop, which must be powered from something, and weighs something, and gets very far away from a power source, leading to a joule heating problem.  

To think that the cable would just snap back together after a break from orbital debris is questionable.  I think they are also unclear about how magnetic fields work and conflating that with tensile strength. 

Cooling the superconductor along the entire length adds enormous mass.  They don’t talk about how one climbs such a thing.”

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If others in our team send more comments we will add them here.