Can we now build the space elevator?

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

In sci.space.policy, on Tue, 31 Aug 2004 19:12:54 -0500, jbuch sez:

` 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....

Well it might hurt to plan for someday that never comes. However, it is a lot of fun to dream (and I do so as much as I can afford to). Space elevators, if in the end profitable, is only the tip of the iceburg for super fibers. The feller who makes this possible would be as important as Bessemer (and hopefully as rich or richer).

If you ever want to say, can you give me change for this million dollar bill, I suggest figuring out how to make cheap ultra strong fibers.

-scott

Dear aSkeptic:

Another hundred years or so, and that'll get you a tank of gas...

David A. Smith

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

Alain Fournier

Macbeth came later, probably around 1200 c.e.

Visualize this: the three witch scene as a Monty Python skit.

Bob Kolker

I hope pennies are discontinued by that time

Materials science isn't my field, but the folks that DO work there seem to be making interesting advances in that area.

the Italians are getting rid of their lira, there's hope for us yet :)

MacBeth was king of Scotland from 1040 to 1057.

The three witch scene did come later. :-)

Alain Fournier

Are getting rid of? er... ok, so where did you leave that time machine parked, again?

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.

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 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.

Vulvox Nano/Biotechnology Corporation is developing the world's toughest, strongest composites to use in the aerospace and other industries. Visit the website at:

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.)

Spam.

Zhu's work is a major breakthrough if confirmed:

Ultralong single-wall carbon nanotubes.

Extra-long carbon nanotubes set new record

20 September 2004 A longer strand of tiny tough stuff.

Bob Clark

snipped-for-privacy@yahoo.com (Robert Clark) wrote in message news:...

news:...

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