Guest essay by Eric Worrall
South China Morning Post has published a claim that Chinese researchers have successfully synthesised a sample of a carbon nanotube material so strong it could be used to construct the tether cable of a space elevator.
China has strongest fibre that can haul 160 elephants – and a space elevator?
Scientists say just 1 cubic centimetre of the carbon nanotube material won’t break under the weight of more than 800 tonnes
Tsinghua University researchers are trying to get the fibre into mass production for use in military or other areas
PUBLISHED : Friday, 26 October, 2018, 12:03am
Stephen ChenA research team from Tsinghua University in Beijing has developed a fibre they say is so strong it could even be used to build an elevator to space.
They say just 1 cubic centimetre of the fibre – made from carbon nanotube – would not break under the weight of 160 elephants, or more than 800 tonnes. And that tiny piece of cable would weigh just 1.6 grams.
“This is a breakthrough,” said Wang Changqing, a scientist at a key space elevator research centre at Northwestern Polytechnical University in Xian who was not involved in the Tsinghua study.
The Chinese team has developed a new “ultralong” fibre from carbon nanotube that they say is stronger than anything seen before, patenting the technology and publishing part of their research in the journal Nature Nanotechnology earlier this year.
“It is evident that the tensile strength of carbon nanotube bundles is at least 9 to 45 times that of other materials,” the team said in the paper.
They said the material would be “in great demand in many high-end fields such as sports equipment, ballistic armour, aeronautics, astronautics and even space elevators”.
…
Those cables would need to have tensile strength – to withstand stretching – of no less than 7 gigapascals, according to Nasa. In fact, the US space agency launched a global competition in 2005 to develop such a material, with a US$2 million prize attached. No one claimed the prize.
Now, the Tsinghua team, led by Wei Fei, a professor with the Department of Chemical Engineering, says their latest carbon nanotube fibre has tensile strength of 80 gigapascals.
…
If this claim is verified by other researchers, the properties of this new material are straight out of science fiction.
Space elevators are the ultimate cheap space launch technology. Instead of blasting into space using a rocket, space elevators allow launch vehicles to literally climb to orbit along a long cable, using electric power supplied via the cable.
The way space elevators work, a satellite is placed in a geosynchronous orbit, and a long cable is dangled down to Earth, where it is tethered to a ground station. Geosynchronous satellites orbit the Earth once every 24 hours, so from the point of view of someone on Earth they appear to permanently hang in the same place in the sky, providing the perfect orbital tether to the top of a very long elevator cable. TV satellites are also placed in geostationary orbits, so you can point your satellite dish at the transmitter, and never have to adjust it again.
The catch is the tether cable has to support its own weight for at least 22,000 miles, so the cable material must be immensely strong and extremely light. The new Chinese nanotube material may satisfy both of these requirements.
Space elevators could be used to construct solar power satellites for an affordable price.
The new material might even make electric cars practical – the Post claims it could potentially be used to construct a flywheel battery for an electric automobile capable of holding 10,000 miles worth of electric charge.
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
Cable instabilities (oscillations) will not allow such things. No way to provide oscillation dampening and still keep cable weight within structural limits.
Agreed, Joel. The more one considers a space elevator, the more issues come to light. I think building a space elevator is as problematic as trying to build a bridge to travel from Europe to America. By the time the technology and funding is acquired to build it, technology for a better way (jet airliners, in that case) has been developed.
A better way to power rockets will probably come sooner than a way to build and run a space elevator.
SR
A bridge from Europe to North America is feasible, though challenging. But first, Europeans would have to drive across Siberia.
https://en.wikipedia.org/wiki/Bering_Strait_crossing
Ha Ha, John, your response should be filed under “You can’t get there from here. (You have to go to another place, first.)”
PS I intended to apply my bridge point to Europeans in Columbus’ time when a bridge across the Bering Strait was just as impossible as one from Spain to America.
SR
I’m still working on my space trampoline.
Calling bs. The strongest chemical bond carbon-carbon is not strong enough to support a string of carbon atoms from geostationary orbit to surface. There is never going to be a ‘space elevator’. It’s another cold fusion zombie project.
The strongest carbon-carbon bond is the triple bond at 962 kJ/mol dissociation energy.
Molar mass of carbon = 12 g/mol
specific strength = dissociation energy/mass = 80,193 kN-m/kg
This is equivalent to 8,178 km breaking length
You could call it ‘The Diamond Tether’ to nowhere.
First of all your counterweight has to be far more out than geosynchroneus orbit to have any ability to lift anything.
Second it has to be very heavy with much more mass than the cargo you would like to lift.
I do not see any way to overcome the reality.
Yes you can create tension in the cable by putting a counterweight beyond geosynchronous orbit. But the strongest material today is colossal carbon tube with breaking length of 6,000 km. Geosynchronous orbit is 35,786 km and the cable must be longer than that. So space elevator is still science fiction.
What could go possibly go wrong putting up a giant lightning rod through the Van Allen belts. And another thing, Earth rotates inside a protective electromagnetic bubble and Earth rotates faster than the upper atmosphere. If a stack of fresh 100’s straight from the bank is 1 metre high , than a billion is * 1000 , then that’s a kilometre stack of 100’s and a trillion dollars IS 1000 K’s of same 100’s. and the mind starts to boggle when applying the above picture to this debt.
“As of September 2014, foreigners owned $6.06 trillion of U.S. debt, or approximately 47 percent of the debt held by the public of $12.8 trillion and 34 percent of the total debt of $17.8 trillion. ” I know the figures are from 2014, but that was the best google could do.
Big, BIG problem – a good proportion of the satellites in near-earth orbit! How could anyone prevent them colliding with the “cable”?
Arm the tether with laser defense!
SR
BUT – this would be a GREAT carbon sync – since IPCC says we need to remove the PPM in atmosphere. Lets do it!! sarc
Wang Changqing? Or is Wang hoping to change his name to Wang Cha-ching for his idea? I think the idea is balls, buckeyballs!
I propose that we imitate the Chinese in their methods of obtaining new technologies. We allow them to work their behinds off while spending huge amounts of money in development and testing. Then we simply steal the finished product thus allowing us to create our own elevator and all of the other products which follow from access to this invention. We could even encourage them in their efforts by lying to them and telling them that we will be one of their first and possibly their best customer. After we have stolen their technology we would also be in a position to sell all of the various products at a much reduced rate than the Chinese as we would not have the need to recoup all of the research and development costs.
This is a common misconception surprisingly even among engineers. The stress in space elevator is not tensile, it’s compressive. Tsiolkovsky, the founder of rocketry and astronautics, is the first person to describe a space elevator in 1903. He understood that the stress is compressive. His design is a very tall building to low earth orbit (200 km altitude)
If the stress is tensile, the cable will pull down the geosynchronous satellite towards Earth and the satellite will fall out of orbit. There is no centrifugal force to counteract the tensile force because centrifugal force is a reaction to centripetal force due to gravity. From Newton’s 3rd law:
centrifugal force = centripetal force
If you add tensile force:
centrifugal force < centripetal force + tensile force
The satellite will fall to Earth
I forgot to say because it should be obvious. Since the stress is compressive, what you need is not a cable but a very stiff rod. A cable is not rigid and practically no compressive strength.
Dr.
You could always climb that stack of hundreds I referenced to above
So basically, these Chinese guys haven’t got a first clue about the topic. On the bright side we may get some rather high performance yo-yo strings out of this. Win! And this is also the most likely source for what Superman’s red undies were made out of.
Has anyone considered the hazard to air traffic of such a cable or cables?
Imagine a commercial or military aircraft striking the cable at 30,000 ft. As well as slicing the plane in two it would do massive damage to the cable(s) or even sever them sending the satellite and elevators flying into space with any occupants on board at the time.
What effective measures could be introduced to avoid such a collision?
The space elevator is a kewl concept but there’s plenty more practical uses to the fiber. i’m thinking of Electrical transmission lines, Tank armour, bycicles.
it would be real nice to ride a 2.5Kg bike.
What practical need is there for electrical transmission cables? We already have long electrical transmission cables.
The weight of the cargo would pull the satellite to Earth it would never work.
The solubility of carbon nanotubes in water is limited and proper amounts of stabilizers are required to avoid flocculation and phase separation. One disadvantage of the CNTs concerning their use in biochemistry and biomedical applications is that they are highly hydrophobic and generally form insoluble aggregates.
https://www.hindawi.com/journals/jchem/2013/676815/
My concern, from the first time I saw a carbon-based Space Elevator mooted is this:
** How do we keep the microbes from eating all that nice Food? **
Be a Real Bummer, to have the thing snap with some nice multi-tonne load halfway to Geosynchronous orbit…
Though it would be more likely to be chewed up in the lowest 10 miles from the ground…
SMASH crunch — well, that was that for the Senator and his entourage….
“Geosynchronous satellites orbit the Earth once every 24 hours” or not, depending if the orbit is ECI or ECEF. 🙂
The Chinese reporting this did not say how long a segment of nanotube fiber they have produced. Most likely it is just long enough to do some sort of tensile test, probably less than a millimeter. When they finish the first kilometer of cable and begin on the second, maybe we will have something.
Yes a space elevator will work if the cable is light enough and strong enough, but these are big “If’s”…
If you believe in space elevators, I feel pity for you.
We have enough trouble with lower orbiting satellites ffs
“The new material might even make electric cars practical – the Post claims it could potentially be used to construct a flywheel battery for an electric automobile capable of holding 10,000 miles worth of electric charge.”
It might work and it would mean a great savings in hospital bills since in any accident bad enough to damage the battery anyone in the car (or nearby) would be vaporized.
Flywheel battery with magic new material is dubious, but graphene has potential applications in improving existing battery technology. This was updated on Oct 24, but latest references appear to be from 2016:
https://www.graphene-info.com/graphene-batteries
Back in 2015, Samsung was thought capable of using its new graphene-enhanced Li-ion batteries to double battery life for Galaxy phones by about now:
https://www.techtimes.com/articles/64353/20150629/samsungs-new-graphene-technology-will-double-life-of-your-lithium-ion-battery.htm
“The way space elevators work, a satellite is placed in a geosynchronous orbit, and a long cable is dangled down to Earth, where it is tethered to a ground station.”
============
Ya gotta be kidding me, right ?
A 22,000 mile trip? That is a long time to listen to elevator music. I keep picturing Jake and Elwood in the elevator at city hall.
If a space elevator had any chance of being practical Elon’s Musk would be all over it. /sarc
So a car with a flywheel storing 10.000 miles worth of energy in it must have quite the gyro mass. What if this car going down the road at a specified speed wants to take a turn or stop, would the gyro mass in the flywheel let the car do it?
Would not the gyro mass force make it go forward at that specified speed in the same direction, no turns or change in speed possible? Same when it is sitting still, enormous force needed to make it go forward, right? Well I am not a scientist I guess, just a farmer but this is what my common sense tells me.
Change in speed will be possible, changing the axis of the gyroscope would not. It would have to be gimballed so it could remain in the same orientation.
The electric potential was from the conductive tether cutting across the Earth’s magnetic field at ~8km/s.
Posted wrong place due to confusion with interface.
The upper part of the cable will permanently in the zone where satellites need an ablation shield to protect the crew, how do we overcome the the constant heat that the cable will be subjected to .
The ablation shield is for re-entry into the atmosphere at high speed. A space elevator would be static relative the Earth and the atmosphere so no frictional heating.