The Ribbon to Space

SkepticJ said:
But when you've spent hundreds of hours drawing, working math problems, writing down and daydreaming new ideas under the false impression that this material will allow them to actually work you can understand the magnitude of my let down. Damn.

(Sigh) You must still be a student. There's a nice Dilbert comic that addresses the moment when your dreams and ideas come crashing down and you become a mindless corporate zombie managed by hopeless idiots. Your day will come. Until then, keep daydreaming and coming up with ideas. Maybe you'll be able to think of a way to save us from ourselves before you join our leagues. ;)
 
I found a Power Point presentation on stresses and defects in nanotubes, but I don't think it has really anything to do with what Matabiri is talking about. Here you go

There, there, SkepticJ. NASA is not trying to decieve you personally. The world of research is a constant game of making your investors and grant providers believe that the next huge money-making breakthrough is only a breath away.-Bruce

I'm assuming from you smilieys that you're kidding. Or are a lot of scientists really that unscrupulous?

So these missing carbon atoms, where do they go? They just fall off or what, or do they not go anywhere but the atomic structure changes slightly at that point opening up the small void?
 
If Matabiri's math is right then carbon nanotubes aren't even close to the strength needed to make a space elevator ribbon. If that's the case why is time and money being wasted on this then? 260 GPa strength give or take would be needed for it to work, and a heafty safety margin above this would be good. So is Nasa and many people at many colleges wasting money on an immpossible dream or Matabiri doesn't know what he's talking about, or both? I'm in a state of bafflement here, somebody help me out.:confused: Estimates that I'm finding for perfect(which have been said already to be unstable and thus not able to be super strong) nanotubes range from about 600 GPa-5.5TPa mostly around 1TPa, so the graph I posted is way off, but may have been up to date when it was new. I don't know. I'm not even training to be a scientist. Graphic Arts is my current path, but science will always be my first love.:) I might not be back until Monday, cheers.
 
SkepticJ said:
Or are a lot of scientists really that unscrupulous?

You need to work on your terminology, SkepticJ. Instead of "unscrupulous", use words like "resourceful", "convincing", "inspirational", "hopeful", and "promising."

Have you ever written a grant before or given a presentation for potential investors? Do you really think anyone is going to write you a check if you included any of the negative sounding replies you've heard on this post.

Most of the people here are intelligent enough to know that the criticisms of the ribbon idea are only trying to point out the potential obstacles involved, not to shoot it down and write it off as unworthy of further work. People that are writing checks for millions of dollars usually don't see it that way. In fact, if I had 1 million dollars and I read this post, there is no way I would fund this research.

If you have an idea and you want to get funding for it, you have to believe in the potential of what you're researching and convince them that you can make it work, especially if you're talking to investors. Investors want that money back, and then some.
 
SkepticJ said:
If that's the case why is time and money being wasted on this then?

I was writing my previous reply when you wrote this one. The above comment really stings. I don't think you understand how research works. Researchers explore new ideas, concepts, and inventions for the love of science, and because what they are doing has never been done before. Do you know how hard it is to get funding for research in today's world?

Nanotubes were only discovered about 10 years ago. We still don't know how to make them affordably, let alone make them into something that can be sold and make a profit. Investors don't often understand how slowly science moves. They want to see returns on their investment almost immediately. So who's left to get the money from? The government, of course.

Most government workers that are signing the checks don't understand science either, but their not trying to make a profit, so the money tends to go to whoever can give the most impressive sales pitch. Having a ribbon dangling from space that a robot can climb sounds like a cool idea. It's no wonder they got money from NASA.

Are they really out to build that ribbon? They don't have to be. All they have to do is continue to work towards it and other scientific achievments are likely to blossom from it.

I'll give you a great example. Tha LASER. The laser was invented in the 1940's. During that time period, every aspect of science that researchers pitched to the government for funding ended with the question, "Yeah, but how can we make it into a weapon?" No descent scientist wants to turn all of his inventions and discoveries into a weapon, but that was the only way to get funding at the time, scrupulous or not. The scientists at the time worked toward building a laser weapon to appease the government, but along the way, other uses were found for it. It took about 40 years for lasers to be developed into bar code scanners and motion sensors, and another 10 years to develop into affordable cd's, DVD's, and hand-held laser pointers. Right now, you can buy a laser cat toy at Petco for $2.

Think about it. If you had gone to the government in 1940 and asked for $50 million dollars to research monochromatic light with the intention of making a $2 cat toy, do you think we would have DVD players today? NOBODY would have predicted that monochromatic light could be used for data storage or even a fraction of the things we use lasers for today.

Don't get discouraged, SkepticJ. You live in a world full of crazy people that don't think like scientists. Good things can come out of telling a few white lies, or red and green lies for that matter. That's how things work outside of the school walls, my friend. ;)
 
SkepticJ said:
It'd have been nice if NASA.gov would have talked about this before they got my hopes up a few years back.:( Nasa is generally a bastion of not blowing the significance of things out of proportion and blowing smoke so I came to trust them. Thought the uber material was just a few decades away. Garrrrrr the trust is tainted and I'm p*ssed!:mad:

Bruce has already answered this far more eloquently than I could, but then he's probably written far more grant proposals than I have.

Nasa is in the business, at least in part, of stimulating the public imagination - and using this to obtain funding for the more mundane. My personal grudge against them is that they killed the breakthrough propulsion physics group two years ago. It wasn't even costing them that much money.

Personally, I'm convinced the space elevator is viable. The physics is sound, it just requires some funky engineering and clever materials. But if it was easy, we'd have done it already, right?

For the carbon chain, I've asked this myself. Bruce can probably give you more details, but as I understand it, having that many double bonds in a row makes the chain highly reactive, and thus prone to bond with other things, breaking the double bonds.

Please don't give up on scientists. We just have to deal with politicians to get money.
 
SkepticJ said:
Estimates that I'm finding for perfect(which have been said already to be unstable and thus not able to be super strong) nanotubes range from about 600 GPa-5.5TPa mostly around 1TPa, so the graph I posted is way off, but may have been up to date when it was new.

The presentation you found also makes the distinction between E (Young's modulus, ~1 TPa) and strength (yield stress, ~150 GPa). E is the stiffness, the ratio of stress to strain during elastic deformation. The yield stress is the stress required for permanent deformation - or fracture, in the case of nanotubes.
 
Bruce said:
I think it's quite a bit far-fetched. Coordinating the stationary orbit of a satellite to lower the ribbon alone is hard enough, but out of curiosity, I did some calculations.

I cut a 2"x 3" piece of ribbon and weighed it: 1 g

2 in x 3 in = 6 in^2

1 g = 0.0022 lb

(0.0022lb / 3 in) * (5280 in / mi) * 60000 mi * (1 ton / 2000 lb) =

116 tons of ribbon

116/6 = 19 tons/in^2

That would have to be one damn strong ribbon to withstand 19 tons of force per square inch!
We have to take inaccount that at high alltitudes the gravity would have lesser impact. Additionally, the device would be hanging in the satalite, also that distributing the weight.

I would say providing they can make large enough mesh, they could build it.

But security would be a problem, how would we restrict airspace around the tube, what happens if the satalite moves a bit, or an earthquake move the foundation.

But it was built, we could have low-gravity labs for undergraduates! Heaven for chemists and molecular biologists!
 
Matabiri said:
The presentation you found also makes the distinction between E (Young's modulus, ~1 TPa) and strength (yield stress, ~150 GPa). E is the stiffness, the ratio of stress to strain during elastic deformation. The yield stress is the stress required for permanent deformation - or fracture, in the case of nanotubes.

So, after factoring in the point flaws what does the strength drop to? 60somethingGigaPascals?

Bruce, sorry I must have forgotten my aphorism.[slaps head] "Fund everything, because you never know where discoveries will come from."-quoting self
 
SkepticJ said:

Bruce, sorry I must have forgotten my aphorism.[slaps head] "Fund everything, because you never know where discoveries will come from."-quoting self

That's the spirit! Now, can I borrow $20 for a case of Guiness? I have discovered some of my best ideas on the bottom of a Guiness bottle. (hic) :alc:
 
SkepticJ said:
So, after factoring in the point flaws what does the strength drop to? 60somethingGigaPascals?

Bruce, sorry I must have forgotten my aphorism.[slaps head] "Fund everything, because you never know where discoveries will come from."-quoting self

The tests in the presentation you posted go up to 60GPa, and they quote 150GPa. But these are for short nanotubes. My instinct tells me, in the absence of real data at the scales and stresses, that you'd need Weibull models for failure. These aren't normally used for composites, as they fail in very energy absorbing ways, but the energies stored elastically at ~260 GPa are going to be far in excess of what can be easily contained.
 
Matabiri said:
Nasa is in the business, at least in part, of stimulating the public imagination - and using this to obtain funding for the more mundane. My personal grudge against them is that they killed the breakthrough propulsion physics group two years ago. It wasn't even costing them that much money.

So that's what happened to that project. I remember reading about it in Popular Science about four or five years ago.

Originally posted by Matabiri The tests in the presentation you posted go up to 60GPa, and they quote 150GPa. But these are for short nanotubes. My instinct tells me, in the absence of real data at the scales and stresses, that you'd need Weibull models for failure. These aren't normally used for composites, as they fail in very energy absorbing ways, but the energies stored elastically at ~260 GPa are going to be far in excess of what can be easily contained.

Are you talking about multi walled or single wall nanotubes? The multi walled ones do fail at around 60GPa, but the single wall ones are supposed to be much stronger; around 200GPa if I'm not mistaken. Something needs to be discovered that can bond with them to make a composite; nanotubes are really slippery.
 
SkepticJ said:
Are you talking about multi walled or single wall nanotubes? The multi walled ones do fail at around 60GPa, but the single wall ones are supposed to be much stronger; around 200GPa if I'm not mistaken. Something needs to be discovered that can bond with them to make a composite; nanotubes are really slippery.

... and the chemistry of the bond will reduce the strength too.

Regarding the strengths, you've probably done much more reading up on nanotubes than I have - I just have issues with the reality of "perfect" molecules on the scales required.
 
Bruce said:
That's the spirit! Now, can I borrow $20 for a case of Guiness? I have discovered some of my best ideas on the bottom of a Guiness bottle. (hic) :alc:

Such as? I must have evidence before I fund your "research".
 

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