Can we now build the space elevator?



I hope pennies are discontinued by that time
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the Italians are getting rid of their lira, there's hope for us yet :)
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Terrell Miller
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Are getting rid of? er... ok, so where did you leave that time machine parked, again?
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Sander

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Err, you don't need a fiber that long.
You need a fiber long enough that the matrix the fiber is in can load the fiber to failure if you pull on the ends of the rope, and also adhered well enough that the ends of each fiber don't pull loose.
Wool twine has a tensile strength of nearly the same as wool fiber, but the individual fibers are only a couple of inches long.
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aSkeptic wrote:

Perhaps you are old enough to remember the earlier "carbon fiber Beanstalk" hype.
If you allow yourself to fantasize that you will be able to get 60% of the theoretical strangth of the graphite crystal..... then you can believe that the "carbon fiber Beanstalk" is feasible.
IT is this belief that one can get these amazing high fractions of the theoretical strength that is the insanity of self delusion.
LOOOONG time to wait for the realization.
HYPE.
JIm
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I don't recall the initial hype over bean stalks or teathers, I think this is before my interest in materials science.
Imagine what would happen if PAN carbon fiber products came down to 1/100th their current (already inflated) cost. PAN fiber is outrageously expensive, last I checked it was about $40 per pound. Weave it in 3 dimentions, pressure infiltrate it with phenolic resin (pitch) and pyrolize it and now you are talking and even more disgustingly expensive material. Lightweight, strong, and solid at high temperatures, C-C composites can be a great material if you can keep oxygen and nitrogen away from it. Last time I looked at carbon fiber it was $40 per pound bulk.
Heck.. If PAN fibers could be made for less than a dollar per pound we might see a revolution in manufacturing. It might not be like the invention of steel, but certainly as important as the invention of aluminum.
And Nanotubes would be even more impressive. I'd prefer boron nitride fibers but I'm not picky. How about a super fiber for less than $1 a pound!
Imagine a twin engine electric powered 4 seat cesna with a pressurized cockpit with less mass than an ultralite. Or Briges spanning nearly a half a mile without any ground supports! You could place a brige anywhere you pleased! Think of what this could do for transportation in big citys. Traffic clogged? Just add a couple more elevated roads. Wouldn't be too great for cars, gotta have some mass to keep it from being blown off the road from a light breaze :)
cheers,
Scott
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aSkeptic wrote:

Perhaps the pitch residue from smoking contributes to wild imagination.
I am an old fart in materials science (first degree in 1053, over 40 years ago), and get put off easily by "NEWCOMER blissful ignorance and speculation".
Jim
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In sci.space.policy, on Tue, 31 Aug 2004 19:12:54 -0500,
` I am an old fart in materials science (first degree in 1053, over 40 ` years ago), and get put off easily by "NEWCOMER blissful ignorance and ` speculation".
OK, I'll play, in what culture is the current year around 1095? And what event are they countng from? Or is this just a case of double transpose typo, and that should have been 1963 - not nearly so interesting....
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vincent@triumf[munge].ca Pete Vincent
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jbuch wrote:

Wow, 1053, impressive. Was that in Scotland under the rule of Macbeth? :-)
Alain Fournier
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Alain Fournier wrote:

Macbeth came later, probably around 1200 c.e.
Visualize this: the three witch scene as a Monty Python skit.
Bob Kolker
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robert j. kolker wrote:

MacBeth was king of Scotland from 1040 to 1057.

The three witch scene did come later. :-)
Alain Fournier
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Materials science isn't my field, but the folks that DO work there seem to be making interesting advances in that area.
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I have devised several methods of manufaturing Ultra Lng carbon nanotubes. This is disussed in greater detail on http://www.vulvoxnanobio.tripod.com Ajayan's process worked in the laboratory but it is not practical. Vulvox Nano/Biotechnology is researching and developing practical processes to manufacture ULNTs (Ultra Long Carbon Nanotubes) Vulvox also has plans to make HTS superconducting nanotube cables and generators. Read my interview published by Nano Investors News the link is on the homepage of the above link.

one-micron
adjustment
http://www.trnmag.com/Stories/2002/103002/Pulling_nanotubes_makes_thread_103 002.html
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The space elevator may be the biggest environmental disaster ever waiting to happen. If an airplane hit the space elevator cable it might drag it into an orbit that causes it to hit the ground. The asteroid that keeps the space elvator in place by centrifiugal force might cause a tidal wave or hit a city with greater energy than a thermonuclear bomb. We should model the space elvator on computers a long time before we can say whether it is a safe project or a disaster movie come true.

one-micron
adjustment
http://www.trnmag.com/Stories/2002/103002/Pulling_nanotubes_makes_thread_103 002.html
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*follow-ups trimmed*
"Neil Farbstein" wrote ...

If it snaps then it will fall under the 'what happens if the cable snaps' category which has been thoroughly considered here* and elsewhere. If it's strong enough to not snap then I'd guess that it could be easily shown to be necessarily too stable to do anything more than 'twang'.

It's only when an asteroid is being manoeuvred towards Earth for capture that it poses any possible threat. Once it's attached the only way it can go (if the elevator snaps) is _out_. Not every design requires an asteroid and I'm sure that any maneuver systems will be very carefully planned to fail 'miss' rather than fail 'hit'.

Interesting that you mention disaster movies - one thing they often have in common is a very loose grasp on facts and an over sensationalist approach.
* sci.space.policy in my case.
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1) The space elevator design most frequently discussed these days is that associated with Brad Edwards -- see "The Space Elevator" (book) on Amazon or an earlier version online at http://www.isr.us/Downloads/niac_pdf/chapter1.html
It is much less massive (~800 tons total) than earlier versions such as that in Kim Stanley Robinson's _Red Mars_ (6 *billion* tons). So it doesn't require an asteroid either as source for cable material or as counterweight... and the worst-case disaster scenarios are nothing like what you're describing.
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Vulvox Nano/Biotechnology Corporation is developing the world's toughest, strongest composites to use in the aerospace and other industries. Visit the website at: http://www.vulvoxnanobio.tripod.com Put it into your address book. We are soliciting investments, strategic partners to jointly research bucktubes, and processes to manufacture them on a large scale. No practical technology of manufactuirng buckytubes exists. We are also developing ultra long carbon nanotubes. This month Dr. Y.T. Zhu at Los Alamos Laboratory published an article in Nature Materials about a brekthrough method of growing ultra long carbon nanotubes. Vulvox is planning to modify Zhu's process to increase its' productivity and to reduce the expense of manuafacturing ULNTs (ultra long carbon nanotubes.)

one-micron
adjustment
http://www.trnmag.com/Stories/2002/103002/Pulling_nanotubes_makes_thread_103 002.html
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Farbstein wrote:

Dead address.

Spam.
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Aidan Karley,
Aberdeen, Scotland,
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Zhu's work is a major breakthrough if confirmed:
Ultralong single-wall carbon nanotubes. http://www.nature.com/cgi-taf/DynaPage.taf?file=/nmat/journal/vaop/ncurrent/abs/nmat1216.html&dynoptions=doi1096137264
Extra-long carbon nanotubes set new record 20 September 2004 http://nanotechweb.org/articles/news/3/9/12/1
A longer strand of tiny tough stuff. http://www.lamonitor.com/articles/2004/09/17/headline_news/news03.txt
Bob Clark
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snipped-for-privacy@yahoo.com (Robert Clark) wrote in message

http://www.nature.com/cgi-taf/DynaPage.taf?file=/nmat/journal/vaop/ncurrent/abs/nmat1216.html&dynoptions=doi1096137264
I found out the calculation of the nanotubes tensile strength is based on using as the cross-sectional area only the single molecule layer of the nanotube as a hollow tube. Note that tensile strength is given in units of pressure, i.e., Force/Area. So using the thickness of the shell of the tube for the area rather than viewing the base of the tube as a filled in disk results in a much higher estimate of the tensional strength. This has consequences for estimating the strength of the tubes when scaled up to macroscopic sizes. For example suppose you wanted to create a cable 10cm wide out of nanotubes bundled together. The weight this cable could support would not be found simply by multiplying the cross-sectional area of the cable Pi*(10cm)^2 times the tensile strength. The reason being the nanotubes are hollow resulting in a much smaller actual total cross-sectional area, and therefore also a much lower strength. So I'm wondering can the nanotubes width be scaled up to macroscopic sizes as is the length? If so, you could have many layers of the tubes one inside the other, fitting close together so there is little empty space, all the way up to centimeter scale widths. Then a 10cm wide cable could be formed in this way and now the cable's cross-section would be filled in and the weight it could support really would be given by multiplying the area of a 10cm wide disk times the tensile strength. However, I've only seen reports of single walled nanotubes at widths up to around 10 nm. Can single walled nanotubes be made arbitrarily wide?
Bob Clark
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