Space Ribbon

4th February 2003, 10:22 PM

I found an interesting article on Wired concerning a proposed "highway" into outerspace.

To the Moon in a Space Elevator?

Sounds incredibly interesting. One of the companies proposing the ribbon is High Lift Systems . Check out their site, and the massive FAQ on their proposed project.

Some interesting tidbits:

The ribbon would be 1 meter wide, and 100,000km long.

The material, carbon nanotubes, would weigh only 7.5kg/km.

If the ribbon somehow broke, the vast majority of it would burn up on re-entry into the atmosphere, and the entire process could take weeks. The substance is so light, it would not cause damage once it fell, due to air resistance.

Cool!

4th February 2003, 10:43 PM

Isn't the Earth spinning to fast for something like that to be feasable?

4th February 2003, 10:48 PM

Quote:

Originally posted by Denise
Isn't the Earth spinning to fast for something like that to be feasable?

Nope. Centripital acceleration would offest the gravity effect. Read the website for a better explaination.

toddjh · 5th February 2003, 12:19 AM

Quote:

Originally posted by SpaceLord
I found an interesting article on Wired concerning a proposed "highway" into outerspace.

I wonder how they intend to erect the beanstalk from the ground up. Space elevator plans I've read before involve starting from geostationary orbit and constructing the beanstalk up and down simultaneously (to maintain the correct center of mass), until the bottom end is low enough to grab onto from the ground.

I also think the director of NASA's Institute for Advanced Concepts saying that it's technically feasible is somewhat misleading. He says there's nothing wrong with the physics, which may be true, but that's a long way from saying that it's within our engineering capabilities, or that it's affordable. The 15 year prediction seems incredibly optimistic, too -- the article says that the materials are "rapidly developing," which is an upbeat way of saying they don't exist yet.

I'd love to see a space elevator -- the ability to get payloads up into space without the need for high-thrust rockets would make it dirt cheap to launch space telescopes, ion-drive-powered probes, and just about anything else you can think of. I just question whether we have the know-how and political will to get it done at this point in time.

Jeremy

5th February 2003, 12:36 AM

Quote:

Originally posted by toddjh

I'd love to see a space elevator -- the ability to get payloads up into space without the need for high-thrust rockets would make it dirt cheap to launch space telescopes, ion-drive-powered probes, and just about anything else you can think of. I just question whether we have the know-how and political will to get it done at this point in time.

Jeremy

True, it is a tall order.But since the complete system may cost less than 20 billions U.S. dollars, the benefit would be incalcuable. It could reduce costs of reaching space to 100$US a kilogram if another, larger cable were to be built off the smaller one.

Many countries and businesses have expressed interest in the project. If the U.N. would agree to cooperate, it would help tremendously. NASA has expressed keen interest as well.

If carbon nanotubes become available in the near future, interest will increase dramtically. I believe it can be done. I imagine the project could get off the ground, so to speak, in the next ten years.

Ove · 5th February 2003, 02:03 AM

Wasn't that an idea off Arthur C. Clarke originally?? But then he thought out the geostationary sattelite years before any rocket flew into space.

davidhorman · 5th February 2003, 02:28 AM

Clarke wrote about it in Fountains of Paradise, which I've just finished reading and is a great book. IIRC the elevator in the book was also a ribbon (or 4 pairs of ribbons) and was also some exotic form of carbon. It was manufactured at a geostationary orbit and lowered to the Earth.

David

fishbob · 5th February 2003, 02:36 AM

Would security have to sniff your shoes before you get on the elevator?

Ove · 5th February 2003, 02:36 AM

Yep, i thought so. I've got to refresh that book asap. Thanks.

5th February 2003, 02:58 AM

Another article

http://www.sciencenews.org/20021005/bob9.asp

bjornart · 5th February 2003, 03:04 AM

Quote:

Originally posted by SpaceLord

If carbon nanotubes become available in the near future, interest will increase dramtically. I believe it can be done. I imagine the project could get off the ground, so to speak, in the next ten years.

That's a fairly big if. The site on nanotubes linked from the article says that state of the art is: With only a few nano-meters in diameter, yet (presently) up to a milli-meter long, the length-to-width aspect ratio is extremely high.

Will the necessary amounts of carbon nano-tube be available in 15 years? (State of the art has to go from millimeters to kilometers.) At a price justifying the construction of a space elevator? I strongly doubt that, even though a space elevator would be soo cool. :-D

Ove · 5th February 2003, 05:25 AM

Quote:

Will the necessary amounts of carbon nano-tube be available in 15 years? (State of the art has to go from millimeters to kilometers.) At a price justifying the construction of a space elevator?

If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close).

If there is a demand for Carbon nano-tubes they will be available, trust me.

bjornart · 5th February 2003, 05:48 AM

Quote:

Originally posted by Ove

If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close).

If there is a demand for Carbon nano-tubes they will be available, trust me.

Well, I quickly found out I was wrong about the length of fibers needed, since they plan to just glue them together. (Which is layman's language for 'embed them in epoxy strips'.) Still, although it pains me to have to distrust you

, demand does not equal guaranteed invention. Fact is science have produced tiny little carbon-nanotubes that have a tremendous strenght/weight ratio. Science has yet to show they can be used to make anything practical, much less something practical for a reasonable price. Until I see proof, I'm going to remain skeptical.

Ove · 5th February 2003, 06:00 AM

Quote:

Until I see proof, I'm going to remain skeptical.

Off course, that's what we are famous for.

Agammamon · 5th February 2003, 06:12 AM

It the elevator breaks, even if only a couple of meters in diameter, it probably won't burn up on the way down. Any material strong enough to withstand the stress of being stretched from the surface to stationary orbit is most likely strong enough to survive reentry. And while the material is light there is an aweful lot of it coming down very fast and say it broke at the counterweight there is enough lenght to wrap around the Earth a couple of times.

On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?).

5th February 2003, 10:39 AM

Quote:

Originally posted by Agammamon
It the elevator breaks, even if only a couple of meters in diameter, it probably won't burn up on the way down. Any material strong enough to withstand the stress of being stretched from the surface to stationary orbit is most likely strong enough to survive reentry. And while the material is light there is an aweful lot of it coming down very fast and say it broke at the counterweight there is enough lenght to wrap around the Earth a couple of times.

On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?).

You might want to read the NIAC report on their website. The carbon nanotubes would burn up on re-entry, there are not designed to withstand the heat of re-entry. The part that did not burn, would fall into the ocean, and it appears from early tests that large strips of the material are not dangerous. The ribbon would fall incredibly slowly, possibly taking weeks to reach the surface.

They plan to construct the ribbon in the ocean, in international waters, west of Equador. It would operate much like a large oil drilling platform, at least at first.

Shadowhawk · 6th February 2003, 10:59 AM

Simply being enormously strong when it comes to stretching doesn't mean it has a high heat capacity or even that it's strong in other ways, like brittleness (Diamond is extremely hard, but it's also rather brittle and cleaves easily--you don't want a knife made out of diamond).

edthedoc · 7th February 2003, 02:18 AM

As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity. The ribbon would most likely break at the mid point between these forces and half would spin out and half would (slowly) drop down.

I might be wrong though.

The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it.

7th February 2003, 08:26 AM

Quote:

Originally posted by edthedoc
As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity. The ribbon would most likely break at the mid point between these forces and half would spin out and half would (slowly) drop down.

I might be wrong though.

The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it.

Carbon nanotubes(CNT) are many times stronger than any other substance. Good quality steel has a tension rating of ~3 Gigapascals. Good quality CNT will have a rating of ~300 GPa. The thickest portion of the ribbon would have to be at the center. The steel cable there would have to be something like 8x10^33 times wider than the rest, while CNT has to be merely 1.5 times as wide as the rest of the ribbon. Calculations predict that the ribbon would need to be able to withstand tensions of ~60 GPa, less than half the rating of any decent CNT.

Sice the ribbon will be less than 1M wide, it would not be an easy task to hit it, and the airspace for many km around it would be a no fly zone; any activity near the ribbon would be highly suspicious. The area west of Ecuador is among the most desolate places on Earth.

Skeptical Greg · 7th February 2003, 08:35 AM

Quote:

Originally posted by Ove

If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close).

If there is a demand for Carbon nano-tubes they will be available, trust me.

Yep'.. We just need the equivalent of a ' Moore's Law ', for nano tubes!!

bignickel · 7th February 2003, 08:46 AM

I doubt that it'll be allowed to happen. The religious yahoos will accuse us (aka rational scientific thinking people) of building another "Tower of Bable."

Since God supposedly trashed the last one, they'll claim a moral imperative and supernatural mandate to destroy this one themselves.

You all remember that religous nut in "Contact"? I think we need to put our house in order before we can do something like this.

Thumper · 7th February 2003, 11:07 AM

=====
You might want to read the NIAC report on their website. The carbon nanotubes would burn up on re-entry, there are not designed to withstand the heat of re-entry. The part that did not burn, would fall into the ocean, and it appears from early tests that large strips of the material are not dangerous. The ribbon would fall incredibly slowly, possibly taking weeks to reach the surface.
=====

Ummmmmm... I'm a little confused here. If it falls slowly, why would it burn up on re-entry? The heating (and subsequent burning up) is caused by the friction between the moving object and the molecules/particles in the atmosphere. If it's not moving quickly, there wouldn't be the necessary number of collisons to heat up the material, thus no burning up upon re-entry.

edthedoc · 7th February 2003, 01:11 PM

I think the correct explanation is that as a single entity it will take a long time to fall to the ground as it is so long, and therefore could be described as falling "slowly". However, like any other object that has mass gravity will take over until air resistance increases to cause the object to fall at terminal velocity i.e. fast enough to burn up.

However, because it would be so long interesting things would happen: the air resistance and effects of gravity around the lower end would be high but both gravity and air resistance at the top end would be low. Don't know what this would do though. Too hypothetical for me.

heath · 7th February 2003, 01:13 PM

Quote:

Originally posted by Ove

If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close).

If there is a demand for Carbon nano-tubes they will be available, trust me.

What makes you think this applies to anything other than CPUs? If this were true of all things then cars would now cost $0.50 and run for 10 years on one tank of gas...

boooeee · 7th February 2003, 01:49 PM

Quote:

Originally posted by Diogenes

Yep'.. We just need the equivalent of a ' Moore's Law ', for nano tubes!!

There's always Hofstadter's law:

Hofstadter's Law : It will always take longer than you think, even if you take into account Hofstadter's Law.

kookbreaker · 7th February 2003, 02:50 PM

So does this mean the elevator Astronauts will not make eye contact with each other on the way up to space?

Ladewig · 7th February 2003, 04:59 PM

Quote:

The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it.

Yeah, before I was halfway down this thread, I could hear the fundamentalists condemning "this tower of Babel - this abomination to God."

Vortex · 8th February 2003, 08:31 PM

Quote:

Originally posted by Agammamon

On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?).

No need for the US to build it in somebody elses back yard. The US already owns both Howland and Baker Islands in the south Pacific right on the equator... just north of American Samoa.

BillyJoe · 9th February 2003, 03:45 AM

Quote:

Originally posted by edthedoc
As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity.

A centripetal force is a force which is directed towards a center.
The centripetal force in this case is gravity which is directed towards the center of the Earth.

And, as we all know, there is no such thing as centrifugal force.
But we do have Newton's first law which is something about the tendency of an object to continue at constant speed in the same direction unless and until it is acted upon by an external force.

When the ribbon breaks, the lower portion will fall down towards the center of the Earth until the surface of the Earth prevents it form falling any further. The upper portion will continue travelling along a tangent to the Earth's surface (actually, it will be a spiral path because of the continuing effects of a progressively diminishing gravitational force)

9th February 2003, 02:51 PM

I just wanted to add that I have been in contact with the CEO of the research company involved in the Space Elevator project. I recently graduated college, and have been unable to find a decent job, the current job market is terrible. If they receive a large grant from NASA, the company plans to hire several people. I would really like to be part of it.

Wish me luck!

xouper · 11th February 2004, 12:36 PM

bump

Dorian Gray · 13th July 2005, 09:49 PM

Bump.

Brad Edwards. Michael Laine. LiftPort Group.

4th February 2003, 10:22 PM	#1
SpaceLord Guest Posts: n/a	Space Elevator/Ribbon! I found an interesting article on Wired concerning a proposed "highway" into outerspace. To the Moon in a Space Elevator? Sounds incredibly interesting. One of the companies proposing the ribbon is High Lift Systems . Check out their site, and the massive FAQ on their proposed project. Some interesting tidbits: The ribbon would be 1 meter wide, and 100,000km long. The material, carbon nanotubes, would weigh only 7.5kg/km. If the ribbon somehow broke, the vast majority of it would burn up on re-entry into the atmosphere, and the entire process could take weeks. The substance is so light, it would not cause damage once it fell, due to air resistance. Cool!
SpaceLord Guest Posts: n/a

4th February 2003, 10:43 PM	#2
Guest Posts: n/a	Isn't the Earth spinning to fast for something like that to be feasable?
Guest Posts: n/a

4th February 2003, 10:48 PM	#3
SpaceLord Guest Posts: n/a	Quote: Originally posted by Denise Isn't the Earth spinning to fast for something like that to be feasable? Nope. Centripital acceleration would offest the gravity effect. Read the website for a better explaination.
SpaceLord Guest Posts: n/a

5th February 2003, 12:19 AM	#4
toddjh Illuminator Join Date: Mar 2002 Location: USA Posts: 3,252	Re: Space Ribbon Quote: Originally posted by SpaceLord I found an interesting article on Wired concerning a proposed "highway" into outerspace. I wonder how they intend to erect the beanstalk from the ground up. Space elevator plans I've read before involve starting from geostationary orbit and constructing the beanstalk up and down simultaneously (to maintain the correct center of mass), until the bottom end is low enough to grab onto from the ground. I also think the director of NASA's Institute for Advanced Concepts saying that it's technically feasible is somewhat misleading. He says there's nothing wrong with the physics, which may be true, but that's a long way from saying that it's within our engineering capabilities, or that it's affordable. The 15 year prediction seems incredibly optimistic, too -- the article says that the materials are "rapidly developing," which is an upbeat way of saying they don't exist yet. I'd love to see a space elevator -- the ability to get payloads up into space without the need for high-thrust rockets would make it dirt cheap to launch space telescopes, ion-drive-powered probes, and just about anything else you can think of. I just question whether we have the know-how and political will to get it done at this point in time. Jeremy

5th February 2003, 12:36 AM	#5
SpaceLord Guest Posts: n/a	Re: Re: Space Ribbon Quote: Originally posted by toddjh I'd love to see a space elevator -- the ability to get payloads up into space without the need for high-thrust rockets would make it dirt cheap to launch space telescopes, ion-drive-powered probes, and just about anything else you can think of. I just question whether we have the know-how and political will to get it done at this point in time. Jeremy True, it is a tall order.But since the complete system may cost less than 20 billions U.S. dollars, the benefit would be incalcuable. It could reduce costs of reaching space to 100$US a kilogram if another, larger cable were to be built off the smaller one. Many countries and businesses have expressed interest in the project. If the U.N. would agree to cooperate, it would help tremendously. NASA has expressed keen interest as well. If carbon nanotubes become available in the near future, interest will increase dramtically. I believe it can be done. I imagine the project could get off the ground, so to speak, in the next ten years.
SpaceLord Guest Posts: n/a

5th February 2003, 02:03 AM	#6
Ove Master Poster Join Date: Aug 2001 Location: Denmark Posts: 2,340	Wasn't that an idea off Arthur C. Clarke originally?? But then he thought out the geostationary sattelite years before any rocket flew into space.
	__________________ I am sitting here, completely surrounded by NO BEER..... (Onslow)

5th February 2003, 02:28 AM	#7
davidhorman Muse Join Date: Oct 2001 Posts: 968	Clarke wrote about it in Fountains of Paradise, which I've just finished reading and is a great book. IIRC the elevator in the book was also a ribbon (or 4 pairs of ribbons) and was also some exotic form of carbon. It was manufactured at a geostationary orbit and lowered to the Earth. David
davidhorman Muse Join Date: Oct 2001 Posts: 968

5th February 2003, 02:36 AM	#8
fishbob Seasonally Disaffected Join Date: Jan 2003 Location: Chilly Undieville Posts: 4,697	Would security have to sniff your shoes before you get on the elevator?
	__________________ When you believe in things you don't understand, then you suffer . . . " - Stevie Wonder Arlen Specter to Alberto Gonzales: "You may be treading on your interdiction and violating common sense, Mr. Attorney General." I hate bigots.

5th February 2003, 02:58 AM	#10
Guest Posts: n/a	Another article http://www.sciencenews.org/20021005/bob9.asp
Guest Posts: n/a

5th February 2003, 03:04 AM	#11
bjornart Graduate Poster Join Date: Nov 2002 Posts: 1,465	Quote: Originally posted by SpaceLord If carbon nanotubes become available in the near future, interest will increase dramtically. I believe it can be done. I imagine the project could get off the ground, so to speak, in the next ten years. That's a fairly big if. The site on nanotubes linked from the article says that state of the art is: With only a few nano-meters in diameter, yet (presently) up to a milli-meter long, the length-to-width aspect ratio is extremely high. Will the necessary amounts of carbon nano-tube be available in 15 years? (State of the art has to go from millimeters to kilometers.) At a price justifying the construction of a space elevator? I strongly doubt that, even though a space elevator would be soo cool. :-D
	__________________ Well, I DON'T CARE WHAT YOU LIKE TO BELIEVE, GODDAMMIT! I DEAL IN THE FACTS! -Cecil Adams

5th February 2003, 05:25 AM	#12
Ove Master Poster Join Date: Aug 2001 Location: Denmark Posts: 2,340	Quote: Will the necessary amounts of carbon nano-tube be available in 15 years? (State of the art has to go from millimeters to kilometers.) At a price justifying the construction of a space elevator? If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close). If there is a demand for Carbon nano-tubes they will be available, trust me.
	__________________ I am sitting here, completely surrounded by NO BEER..... (Onslow)

5th February 2003, 05:48 AM	#13
bjornart Graduate Poster Join Date: Nov 2002 Posts: 1,465	Quote: Originally posted by Ove If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close). If there is a demand for Carbon nano-tubes they will be available, trust me. Well, I quickly found out I was wrong about the length of fibers needed, since they plan to just glue them together. (Which is layman's language for 'embed them in epoxy strips'.) Still, although it pains me to have to distrust you , demand does not equal guaranteed invention. Fact is science have produced tiny little carbon-nanotubes that have a tremendous strenght/weight ratio. Science has yet to show they can be used to make anything practical, much less something practical for a reasonable price. Until I see proof, I'm going to remain skeptical.
	__________________ Well, I DON'T CARE WHAT YOU LIKE TO BELIEVE, GODDAMMIT! I DEAL IN THE FACTS! -Cecil Adams

5th February 2003, 06:00 AM	#14
Ove Master Poster Join Date: Aug 2001 Location: Denmark Posts: 2,340	Quote: Until I see proof, I'm going to remain skeptical. Off course, that's what we are famous for.
	__________________ I am sitting here, completely surrounded by NO BEER..... (Onslow)

5th February 2003, 06:12 AM	#15
Agammamon Graduate Poster Join Date: Jan 2003 Posts: 1,302	It the elevator breaks, even if only a couple of meters in diameter, it probably won't burn up on the way down. Any material strong enough to withstand the stress of being stretched from the surface to stationary orbit is most likely strong enough to survive reentry. And while the material is light there is an aweful lot of it coming down very fast and say it broke at the counterweight there is enough lenght to wrap around the Earth a couple of times. On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?).
	__________________ It will be a great day when the US Air Force has all the bombs it needs and the NEA has to hold a bake sale in order to pay its lobbyists.

5th February 2003, 10:39 AM	#16
SpaceLord Guest Posts: n/a	Quote: Originally posted by Agammamon It the elevator breaks, even if only a couple of meters in diameter, it probably won't burn up on the way down. Any material strong enough to withstand the stress of being stretched from the surface to stationary orbit is most likely strong enough to survive reentry. And while the material is light there is an aweful lot of it coming down very fast and say it broke at the counterweight there is enough lenght to wrap around the Earth a couple of times. On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?). You might want to read the NIAC report on their website. The carbon nanotubes would burn up on re-entry, there are not designed to withstand the heat of re-entry. The part that did not burn, would fall into the ocean, and it appears from early tests that large strips of the material are not dangerous. The ribbon would fall incredibly slowly, possibly taking weeks to reach the surface. They plan to construct the ribbon in the ocean, in international waters, west of Equador. It would operate much like a large oil drilling platform, at least at first.
SpaceLord Guest Posts: n/a

6th February 2003, 10:59 AM	#17
Shadowhawk Scholar Join Date: Aug 2001 Posts: 55	Simply being enormously strong when it comes to stretching doesn't mean it has a high heat capacity or even that it's strong in other ways, like brittleness (Diamond is extremely hard, but it's also rather brittle and cleaves easily--you don't want a knife made out of diamond).
Shadowhawk Scholar Join Date: Aug 2001 Posts: 55	__________________ Shadowhawk "Sufficiently advanced technology is often indistinguishable from magic." -- Clarke's Third Law

7th February 2003, 02:18 AM	#18
edthedoc Thinker Join Date: Dec 2002 Posts: 165	As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity. The ribbon would most likely break at the mid point between these forces and half would spin out and half would (slowly) drop down. I might be wrong though. The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it.
edthedoc Thinker Join Date: Dec 2002 Posts: 165

7th February 2003, 08:26 AM	#19
SpaceLord Guest Posts: n/a	Quote: Originally posted by edthedoc As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity. The ribbon would most likely break at the mid point between these forces and half would spin out and half would (slowly) drop down. I might be wrong though. The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it. Carbon nanotubes(CNT) are many times stronger than any other substance. Good quality steel has a tension rating of ~3 Gigapascals. Good quality CNT will have a rating of ~300 GPa. The thickest portion of the ribbon would have to be at the center. The steel cable there would have to be something like 8x10^33 times wider than the rest, while CNT has to be merely 1.5 times as wide as the rest of the ribbon. Calculations predict that the ribbon would need to be able to withstand tensions of ~60 GPa, less than half the rating of any decent CNT. Sice the ribbon will be less than 1M wide, it would not be an easy task to hit it, and the airspace for many km around it would be a no fly zone; any activity near the ribbon would be highly suspicious. The area west of Ecuador is among the most desolate places on Earth.
SpaceLord Guest Posts: n/a

7th February 2003, 08:35 AM	#20
Skeptical Greg Philosopher Join Date: Jul 2002 Location: Just past ' Resume Speed ' Posts: 8,843	Quote: Originally posted by Ove If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close). If there is a demand for Carbon nano-tubes they will be available, trust me. Yep'.. We just need the equivalent of a ' Moore's Law ', for nano tubes!!
	__________________ A quantum of solace, is better than no solace at all.. " Don't come home a' drinkin' , with lovin' on your mind "... Loretta Lynn

7th February 2003, 08:46 AM	#21
bignickel Mad Mod Poet God Join Date: Aug 2002 Location: St. Louis, MO Posts: 2,582	I doubt that it'll be allowed to happen. The religious yahoos will accuse us (aka rational scientific thinking people) of building another "Tower of Bable." Since God supposedly trashed the last one, they'll claim a moral imperative and supernatural mandate to destroy this one themselves. You all remember that religous nut in "Contact"? I think we need to put our house in order before we can do something like this.
	__________________ "You can find that book everywhere and the risk is that many people who read it believe that those fairy tales are real. I think I have the responsibility to clear things up to unmask the cheap lies contained in books like that." - Cardinal Tarcisio Bertone

7th February 2003, 11:07 AM	#22
Thumper Thinker Join Date: Feb 2003 Posts: 234	Burning up? ===== You might want to read the NIAC report on their website. The carbon nanotubes would burn up on re-entry, there are not designed to withstand the heat of re-entry. The part that did not burn, would fall into the ocean, and it appears from early tests that large strips of the material are not dangerous. The ribbon would fall incredibly slowly, possibly taking weeks to reach the surface. ===== Ummmmmm... I'm a little confused here. If it falls slowly, why would it burn up on re-entry? The heating (and subsequent burning up) is caused by the friction between the moving object and the molecules/particles in the atmosphere. If it's not moving quickly, there wouldn't be the necessary number of collisons to heat up the material, thus no burning up upon re-entry.
Thumper Thinker Join Date: Feb 2003 Posts: 234

7th February 2003, 01:11 PM	#23
edthedoc Thinker Join Date: Dec 2002 Posts: 165	I think the correct explanation is that as a single entity it will take a long time to fall to the ground as it is so long, and therefore could be described as falling "slowly". However, like any other object that has mass gravity will take over until air resistance increases to cause the object to fall at terminal velocity i.e. fast enough to burn up. However, because it would be so long interesting things would happen: the air resistance and effects of gravity around the lower end would be high but both gravity and air resistance at the top end would be low. Don't know what this would do though. Too hypothetical for me.
edthedoc Thinker Join Date: Dec 2002 Posts: 165

7th February 2003, 01:13 PM	#24
heath Thinker Join Date: Oct 2001 Posts: 152	Quote: Originally posted by Ove If you try going 15 years back and look at CPU size/price it sounds very plausible. In 1988 the CPU was a 8086 and a PC cost 4-6000$ (OK i'm shooting straight from memory but i think i'm pretty close). If there is a demand for Carbon nano-tubes they will be available, trust me. What makes you think this applies to anything other than CPUs? If this were true of all things then cars would now cost $0.50 and run for 10 years on one tank of gas...
heath Thinker Join Date: Oct 2001 Posts: 152	__________________ <small>This space intentionally left blank</small>

7th February 2003, 01:49 PM	#25
boooeee Dart Fener Join Date: Aug 2002 Location: The Lando System Posts: 1,778	Quote: Originally posted by Diogenes Yep'.. We just need the equivalent of a ' Moore's Law ', for nano tubes!! There's always Hofstadter's law: Hofstadter's Law : It will always take longer than you think, even if you take into account Hofstadter's Law.

7th February 2003, 02:50 PM	#26
kookbreaker Evil Fokker Join Date: Aug 2001 Posts: 6,578	So does this mean the elevator Astronauts will not make eye contact with each other on the way up to space?
kookbreaker Evil Fokker Join Date: Aug 2001 Posts: 6,578	__________________ My Webstore of Telescopes, Science Fun, and More: Spectrum Scientifics! Spectrum Scientifics Store Blog!

7th February 2003, 04:59 PM	#27
Ladewig Philosopher Join Date: Dec 2001 Location: Gulf Coast Posts: 8,560	Quote: The other more modern problem is that of some stupid idiot trying to crash into it, but then if it's strong enough to exist, an aircraft would probably be sliced in two when it hit it. Yeah, before I was halfway down this thread, I could hear the fundamentalists condemning "this tower of Babel - this abomination to God."
	__________________ When I see all the kooky things posted on the JREF forums, I can't help but think of Max Bialystock's lament: "They come here, they all come here, how do they find us?"

8th February 2003, 08:31 PM	#28
Vortex Thinker Join Date: Feb 2003 Location: Texas Posts: 151	Quote: Originally posted by Agammamon On a more practical note; The elevator will need to be constructed near the equator. If say the US built it we would most likely be in the same situation as when we built the Panama Canal (large expensive project in somebody elses backyard, how long could we keep control of it?). No need for the US to build it in somebody elses back yard. The US already owns both Howland and Baker Islands in the south Pacific right on the equator... just north of American Samoa.

9th February 2003, 03:45 AM	#29
BillyJoe Penultimate Amazing Join Date: Aug 2001 Location: MOOROOLBARK Posts: 11,622	Quote: Originally posted by edthedoc As per Clarke's excellent book, half the structure would be in a constant state of trying to spin out into space due to centropetal force exceeding gravity. A centripetal force is a force which is directed towards a center. The centripetal force in this case is gravity which is directed towards the center of the Earth. And, as we all know, there is no such thing as centrifugal force. But we do have Newton's first law which is something about the tendency of an object to continue at constant speed in the same direction unless and until it is acted upon by an external force. When the ribbon breaks, the lower portion will fall down towards the center of the Earth until the surface of the Earth prevents it form falling any further. The upper portion will continue travelling along a tangent to the Earth's surface (actually, it will be a spiral path because of the continuing effects of a progressively diminishing gravitational force)
	__________________ A secular society is one in which no one loses any liberty as a consequence of someone else's religious beliefs. NB

9th February 2003, 02:51 PM	#30
SpaceLord Guest Posts: n/a	Crossing Fingers! I just wanted to add that I have been in contact with the CEO of the research company involved in the Space Elevator project. I recently graduated college, and have been unable to find a decent job, the current job market is terrible. If they receive a large grant from NASA, the company plans to hire several people. I would really like to be part of it. Wish me luck!
SpaceLord Guest Posts: n/a

11th February 2004, 12:36 PM	#31
xouper Banned Join Date: Jan 2002 Posts: 2,189	bump
xouper Banned Join Date: Jan 2002 Posts: 2,189

13th July 2005, 09:49 PM	#32
Dorian Gray Hypocrisy Detector Join Date: Nov 2002 Location: Dayton, Ohio Posts: 9,638	Bump. Brad Edwards. Michael Laine. LiftPort Group.
	__________________ "A little nonsense now and then is relished by the wisest men." - Willy Wonka "Rational arguments don't work on religious people. If they did, there wouldn't be any religious people." - House You are dead to me, with ketchup of little consequence obtusely, portending a silver azimuth, crushing the quasi-sovereign birdcage into Bolivia.