Discussion on:

Going up? Take an elevator ride to space

What happens if someone flies a plane (intentionally or unintentionally) into these tubes? What if this happens while a load is on its way into space? It seems like terrorists could have a field day with something like this.

One way to handle a terrorist cutting it would be to have a way to cut loose portions of the counterweight. If you can keep its center of gravity geosynchronous after it has been cut, it will happily continue to orbit there.

It depends on where on the elevator the terrorists hit. The elevator has to go from earth surface to some distance past geosynchonous orbit to keep the cable tight. A break near earth would cause the whole thing to fly out from centrifugall force, a break towards the middle and the outer sections flys away and the lower section collapses like a series of meteroids smashing into earth. There are several sci-fi stories based on a space elevator; the one I think of for this problem with space elevators is Kim Stanley Robinson's Mars series "Red Mars", "Green Mars" and "Blue Mars" about terraforming Mars.

I don't see a plane strike doing any damage to this material. Much like a bullet can't penetrate a silk cloth because the silk is too light and too strong. Carbon Nanotube fibre is 100 times stronger than silk.
This fibre can support a car with a thread that is too small to see! In those early tests, they quickly realized accidental contact with that tight thread caused horrible wounds! You could hit it with a baseball bat and cleave the bat!
A plane hitting this cable would just receive a large dent and then take the cable with it.. The plane would severely loose speed and, after about 200 meters, would spin off. This is also the reason the cable would be located mid ocean with closed air space and a defended support platform.

Amazing. This is what you think about? Looks like the terrorists won.

"What if" is the excuse for doing nothing. What if I go out to get in my car and a tree falls on me? I should not go out; I should stay inside. What if there is a gas leak in my house and it explodes? I should not stay inside; I should go out. I'm so confused ... I am locked in a set of 'what if' tragedies and disasters .... Oh, there is no escape .... what to do, what to do .............

The engineer in me asks what happens when the elevator gets stuck between the two end points? How do you fix it with people on board and imagine the wait time for the repair crew?

As one Engineer to another, this isn't an elevator cab which is either a cable suspended or a hydraulic lifted cab. The plan for a space elevator has always been to have several cables, with an electric current in conductors inside the cables creating an electric field, then using magnets in the cars to run up the cable as a linear motor. Presumably, the cars would draw power from other wires in the cable too.

What I wonder about is the limiting of the car to 200 KPH. This would make sense in the atmosphere. Vibrations would be induced in the cables by winds. Once above the atmosphere, there is no reason to limit the cars speed. It could then accelerate up to any reasonable speed. It would of course have to decelerate at the top too. But, speeds of up to 5000 KPH would appear reasonable once you are more than say 150 KM above ground level. It would be a comfortable trip if you kept the acceleration down to around 12 M/S^2. Changeover would be uncomfortable, as the room would seem to flip from right side up to upside down, but a simple gimbals system would make that easier to take. A quick back of the envelope calculation would give a total trip time of only a few hours. Less than the time for a subsonic transatlantic trip.

The thing would be a power hog. Existing conductors are not up to the task of the power levels that would be needed. You would probably want to power the system from both space and from the ground. The electrical coordination required would be quite interesting.

The existing nano tube fiber systems are not near the strength required for the systems yet. Nano tube fibers to date are not very long. They are also quite flammable. Yes, they will cut steel or even titanium. No need to worry about the fictional terrorists cutting the cable with an aircraft. It would take a laser. But, the cable would burn very well.

Current tether materials are more plastics with the carbon nano tubes embedded. This has the advantage of both binding the little things, and protecting them from the oxygen. This approach has yielded tethers of over a kilometer in length. But, the strength is only a little better than steel. Much work remains to be done on tether materials.

The Space Elevator will need something that can be responsive to vibration dampeners in the atmosphere, resistant to impacts from orbital debris, as well as resistant to UV radiation and cosmic rays. It would also have to have better bonding of the carbon nano tubes into the matrix, and be able to increase the amount of nano tubes in the matrix. It's an interesting materials problem.

Progress is being made though. The sort of material needed will be useful for many construction projects here on Earth too. It will be a wonderful tension member. It can provide great compression strengthening too by having a non compressible material inside a wrapping of this material. Tether wrapped concrete columns would enable mile high buildings to be much lighter. It would enable much longer bridge spans. It would also enable structures that are not currently possible.

The biggest hurdle to developing the basic system is to be able to reliably produce the long strands of carbon nano tubes for inclusion in the matrix.

The material for the power wiring is another fascinating area for consideration. a room temperature superconductor would be ideal. A material that doesn't super-conduct might be necessary, but I would want a material with lower resistance than copper wire.

All of these details are why Aurthur C Clark said it would take 50 years after people stopped laughing before it was done. they stopped laughing 5 years ago.

but I gave it a big "thumbs down" for being longer than the article itself. Reel it in, Bob.

"What do you think? Is this just another example of trying to create science fiction fantasies in real life? Or would such an elevator have real value?"

The more obvious question: Is this just another example of a company creating free advertising/PR at the expense of the media and their readers - because the media editors aren't bright enough to understand that no serious business attempts to work off a 50 year plan. Most can't meet the goals of a 5 year plan. Way to be used not-so-Smart Planet.

It's been a popular SF idea for years, and you zeroed in on the one problem, material strength. We just don't have anything with the right strength and weight characteristics right now. As for what happens if a plane flies into the elevator, it's hard to imagine the size and strength required. I wouldn't want to be in what was left of the plane, and the beanstalk would be pretty much unscathed. As for the fuel burning, yes, nanotubes are carbon and could cook off, but you won't see a 9-11. There are too many ways to dissipate the heat.

A functional beanstalk would make a lot of things possible and aid in raising the quality of life down on the planet.

But, I would only take such a trip if it would actually go somewhere, like a different plannet or something... Not a spacestation, where everything looks just as boring as the trip...

I don't claim to know everything about nanotubes, but I believe that they are grown. Wouldn't it be possible to just have them grow below the factory and raise it into space?
How quickly can they be made to grow?
It would be a hefty and precise build/grow project.

You could also potentially grow a carbon nanotube and splice it to another, then you could parallelize the process. By simply growing 1000 sections at a time and splicing, you could have the fiber growing at about 1000 times the actual growth rate.

May A. C. Clark RIP, but this idea is impossible. Even diamond filaments wouldn't stand the stress, even if they could be manufactured. Worse, this thing would necessarily have to be constructed in geostationary orbit, and the fibers be shielded from the impact of micrometeoroids and space junk. At several hundred dollars per Kg of payload, the thing would cost more money than has ever existed.

There is little reason to go on about "cost" or "money". At this point in the history of the world, money doesn't exist. What exists is "opportunity" that is printed in the form of what used to be called money. World banks and governments control the expansion on the planet by using "interest rates" as a deterrent to rate of growth. The lower interest rates are at the Fed and other "world banks", the more opportunity there is to do something, because you don't have to pay it back with any great "loss". The world truly is now a socialist economy that is being ran by the bank's dictatorial policies. They try to do the right things, it seems, by managing the rate of growth based on the stock market, population and perceived "inflationary pressures".

But, in the end, all that is really happening, at this point, is the lack of "projects" is limiting the employment on the project, and that is directly related to the "interest rates" at the bank, and our in abilities to have long term views on projects, such as this one, which it wouldn't really matter if we were able to complete. Instead, it would employee 10's of thousands of people with a job to complete, money to be made, and things to keep lots of parts of the world employed doing.

It's time for us to really start understanding that the way we view capitalism and opportunity really has lots of issues with how successful we can be at keeping the world running.

We need large scale projects that aren't "WAR", which is what has been the single largest employer we've had. We need to try space exploration from a different perspective than "jump to orbit and look at the earth". NASA's small vehicle projects, going out to look at lots of different things will be very educational, and hopefully reveal some rather amazing things, right here, close by.

But, with gravity as our barrier, we can't get much "mass" off the planet to go do anything "long term". Instead we have all these 1-2 week outings to orbit, and that's all we do, over and over and over...

How long do you think our societies can survive on "build cars", "build houses", "grow food", "birth another baby", "bury another relative", buy another stereo, get the latest iphone etc?

There is much more in the universe that we could be discovering... We waste an awful lot of time, energy and ohh, that "money" stuff on completely useless things.

The missing element in your "analysis" is the fact that WHATEVER we manufacture, it must be done using actual RESOURCES mined, grown, or put together by us, here on Earth.

Money IS a collective fantasy, true; and its also true that various tricks can generate more money and "economic activity" out of simple traded information.

BUT...

To DO anything with that money, we still need resources.

So while we are blithely using (up) the resources of the planet, in order to send some few privileged humans out into the solar system, the REST OF US, here on the formerly pristine planet that gave us birth, will be sinking deeper and deeper into a stew of that project's waste products.

How much is it worth, to follow our immature dreams? No one actually COUNTS in a dream -- not beyond three, anyway. By the time a thousand people have gone up the beanstalk to a "better" life in space or on other planets, the bill that comes due for that collective endeavor will have cost the rest of us litterally trilliooo,ooo,ooo,ooons of dollars, and probably millions of lives, in the final analysis.

And without the indefinite continuation of such a benighted policy, the effort will still evaporate into stardust, when the support is withdrawn.

No, money is a way of counting things, and comparing their value.

Thinking that we can spend an infinite amount of money wastes a lot of resources. Everything you or I do is trading some value (mostly our time and talents) for something someone else did. What we are doing is not making money something you don't have to worry about, it's really just changing the way we track it. (we have gone from valuable metals to paper and now to bits.) It doesn't change the reality of what we are tracking, however. If you want to say that it does, you are just making your money (and mine probably) become worthless.

It doesn't matter if you want to take the money spent on arms and use it to buy food. That doesn't change the amount of food there is, it also doesn't change the value of the unused metal. It does though, deprive the metal workers now producing tanks of a means of supplying their families with what they need. Ever try to eat a tank? It isn't very nutritious.

I do like the idea of settling space. I don't however delude myself that we can just spend without paying off or paying back the sources of the money.

Yes, the resources expended in a small war would be enough to pay for a colony on the Moon with a population similar to that of Wyoming. But it would still be an expense that would ultimately have to be either paid, or have the sponsoring society harmed to that amount.

Money may be 'imaginary', but it represents real work and real resources.

Don't be misled. Every Cent must be accounted for, or you are harming someone.

I like this long view and the not war part now if we can just get everyone to cooperate.

Starman35, this has been studied by physicsists and chemists as well as astronomers. At the ground, the tether would be a ribbon around a meter wide, and only a couple of millimeters thick, except for where the power and communications cables are installed. It would taper up in thickness to the station, then taper off after the station. If Carbon Nano tubes (pure) are used, it would be around 30 Meters across at the station. If Diamond were used, it would have to be thicker, around 150 Meters across at the station. If Tungston Steel were used, it would have to be around 2 Meters across at the ground end, and taper up to around 5 KM across at the station.

There are ranges of size needed that are dependent on the tensile strength of the material used. Even spider silk has been considered. The problem there is that the strength of the silk requires water in the bonds. It would have to be encapsulated. Spider silk is about 10 X stronger than steel in tension. That's better than we get with current tether materials, but less than the carbon nano tubes are capable of.

It probably won't be possible to build until after we already have colonies in space. It's much easier to build it in place and then lower it to the ground.

So it is possible, will be profitable, but not in your lifetime. It's long range research at this point. But, research has spinoffs.

There will be whole new industries in the next 20 years or so from this effort.

This is a new take on "Stairway to Heaven"...if one would desire to leave planet earth, why on "earth" do it in a tube that takes a week to get wherever it's going and BTW...what is the destination again?

The waiting room, of course, the official name for which will probably be Earth Terminus 1 or some such. I wouldn't speculate on what it would receive for a nickname...

Once you achieve earth orbit you are halfway to anywhere in the solar system in terms of delta V. Imagine cutting the first two stages off the giant Saturn V rockets we used to send our astronauts to the moon. We could also use rotating beanstalks orbiting the moon and just barely touching down at the surface to transport people and materials to and from the lunar surface. Rotating beanstalks located
throughout the solar system could convert speeds of vehicles simply by docking at the middle point and then traveling out to the end before casting off with a -much- higher speed. Or slow them down by reversing the process. We could fly around the solar system like in a pin ball machine. Beanstalks would not work on Venus because the length of the day and the rotational velocity is unsuitable. Think of transporting millions of tons of material up and down the stalk with zero pollution and no energy drain from earth as all the solar power we could ever use could be coming down on superconducting cables from orbiting solar power stations and from the electrical differences between earth and the other end of the cable. There are incredible fortunes to be made in space, things and new processes we can't even begin to imagine. I just hope we have the guts and intellect to get in on it and not to leave it to the Chinese and Japanese to exploit. And they certainly -will- do it whether we participate or not.

Where can I get some of the stuff you're smoking? Get back to your bong, hippie.

Space elevator from earth, I don't think it is a good idea. You right, Terrorist could have a lot of fun with it but there is a lot of space junk also that could hit it. I thought we check out this idea years ago? and the cost of making it safe was too high.