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Space Ribbon

SpaceLord

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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!
 
Isn't the Earth spinning to fast for something like that to be feasable?
 
Denise said:
Isn't the Earth spinning to fast for something like that to be feasable?
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Nope. Centripital acceleration would offest the gravity effect. Read the website for a better explaination.
 
SpaceLord said:
I found an interesting article on Wired concerning a proposed "highway" into outerspace.
Click to expand...

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
 
Re: Re: Space Ribbon

toddjh said:

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
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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.
 
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. ;)
 
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
 
Yep, i thought so. I've got to refresh that book asap. Thanks.:D
 
SpaceLord said:

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.
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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
 
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?
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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. ;)
 
Ove said:


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. ;)
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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. :D
 
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?).
 
Agammamon said:
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?).
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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.
 
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).
 
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 said:
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.
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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.
 
Ove said:


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. ;)
Click to expand...

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