OT: About Space Elevators
 

Just FYI since we've discussed adding Space Elevators to the game, you can get a huge amount of information about how practical it would be to build one for Earth right now by visiting www.highliftsystems.com -- especially the downloads sections where lots of PDF and Word files are available with technical information.

Re: OT: About Space Elevators
 

What happens if the Space end of the ribbon breaks Geosynchronus orbit by whatever unknown reason even for a second?

And what happens if the Ribbon breaks?

And will it be accesable to everyone?

Three reasons Why I don't like the idea of a space elevator.

Re: OT: About Space Elevators
 

I got a friend who's always taking about this, and I just don't get it. How is it better that launching things.

I may be a dense old chemist, dregeing up high school physics but, isn't the energy needed the same no matter how you achieve orbit? How do you adapt the terrestrial end to things like chanes in the earth's surface due to tidal forces. How do you maintain something that long. Doesn't air resistance still affect things on their way up?

I want simple questions like this answered before I wand through a bunch of plans.

[ October 09, 2002, 00:39: Message edited by: Arkcon ]

Re: OT: About Space Elevators
 

Will it survive a colision with a fully laden 737?

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">It's quite simple actually. The amount of energy to get X tons into space is the same, but the energy can be generated on the planet, or in orbit, and transfered to the elevator through the cable itself. The elevator can have a realatively small and simple electric motor and receive joice form the cable. So you don't have to carry the fuel in the vehicle going up.

The weight of the fuel in a conventional orbital launch vehicle is a great majority of the total weight of the vehicle. And the more fuel you have, the more you need to carry the fuel, and so on.

Tidal stresses, air resistance, and other things are serious problems. Coming up with materials and designs that can handle those loads is the main stumbling block to acheiving something like this.

<font size="2" face="Verdana, Helvetica, sans-serif">It won't go flying off into deep space if that's what you are asking. The cable doesn't hold the orbital vehicle down. In effect the sattelite/cable combo beceoms a verry long sattelite circling the earth over one spot, which it just happens to touch.

If it breaks, it would likely be a bad day for anyone that happens to be where it decides to land. That danger would likely be lessened greatly by the location chosen. They would put it where if it did fall it wouldn't land on populated areas. It wouldn't even have to be over water, although that would be safest. Given a likely altitude of the orbital end of 250 to 300 miles. There are some over land areas that would be safe.

And is any space travel accesable to anyone? But the costs invovled in this would be so low it would make orbit within reach of many that have no hope now.

<font size="2" face="Verdana, Helvetica, sans-serif">Is that supposed to be a joke? No, it won't. But what will? Not much. But if it were the target of a terrorist attack it would likely be very expensive in terms of cost, but not nearly so in terms of lives lost as the World Trade Towers.

Geoschmo

[ October 09, 2002, 01:08: Message edited by: geoschmo ]

Re: OT: About Space Elevators
 

Actually, to rephrase my question:

What happens to the people/goods that are on the ribbon if the Space end of the ribbon breaks Geosynchronus orbit by whatever unknown reason even for a second?

And also, they wouldn't make a ribbon out of fabric; will there be some kind of massive whiplash?

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">The elevator itself would most likely have some sort of parachute recovery system. That's not a big deal wieght wise or technologically. We can do that now. A much bigge concern is what would happen to the ribbon itsself, or more precisley anyone it falls on. No matter how light it is, 300 miles of it is going to be heavy.

Re: OT: About Space Elevators
 

Instead of asking these questions here you should visit the site and you'll find the information. That's why I posted the site. Nevertheless, I'll try to answer some of these questions.

The Space Elevator is basically a very long cable that stretches from a space station in geosynchronous orbit to the ground. The point of ground contact must be very close to the equator, of course, and that limits where it can be setup.

Although... there has been talk of using some fancy engineering to make 'diagonal' cables from temperate lattitudes meet several hundred miles up and then connect to the single cable coming from the large station in geosynchronous orbit. Once you got it setup it would work as well as the single cable system. The problem is in setting it up! http://forum.shrapnelgames.com/images/icons/icon7.gif

There are several reasons this is an easier way into orbit than rockets or other launch vehicles. The first is simply that you don't have to push so hard to go up! Heating thousands of tons of gas to very high temperatures by combustion so they will bLast you upward in the process is very inefficient, not to mention dangerous. With the space elevator you could have an electric motor more-or-less like those on current elevators in high-rise buildings. Or perhaps a 'pneumatic tube' type system with the air being pumped up to the station serving to propel the elevator as well! http://forum.shrapnelgames.com/images/icons/icon10.gif Anyway, not having to gain speed by 'throwing' stuff away from yourself at high speed is both more efficient and safer. If the elevator cars are 'external' to the cable then you also have to deal with air resistance but this is better with the cable than with rockets as well. You also don't have to go for super-sonic speed right away. Obviously it will be a long ride into orbit if the whole trip is at standard elevator speeds http://forum.shrapnelgames.com/images/icons/icon12.gif but it's best not to go more than a few hundred miles an hour for the first 50,000 feet or so. After that you can go thousands of miles an hour with no major air resistance problems. Not having to fight the atmosphere or design for the heating from friction makes the elevator cars much cheaper than rocket vehicles. If the elevator will be inside the cable (more difficult but we'll probably do that eventually) then you could evacuate the air and use the 'pneumatic tube' effect as I mentioned before.

The possible accidents and problems are many of course. If the cable breaks somewhere up in orbit and loses 'equilibrium' so that it comes down, it will cause damage across hundreds or thousands of miles of terrain. It's got to be made of incredibly strong materials so it will probably destroy anything it comes down on, crashing at orbital speeds. If the whole cable comes down it would wrap almost all the way around the earth!

The 737 question is not such a problem as you might think. A modern jet airliner is basically a huge aluminum ballon. It's very fragile and the cable is very strong. An airliner would be sliced up if it hit the cable but probably do little damage. More dangerous would be a hit on the ground link where an explosion and fire might damage the anchorage. I think the elevator 'cars' will be far more vulnerable than the cable itself. They cannot be heavily armored without increasing costs quite a bit. They are rather similar to jet airliners in that respect! A small bomb could punch a hole in one when it's part way up and expose everyone inside to the vacuum of space. This could be at least as tricky to guard against as it is for airlines since explosives have become so high-tech and difficult to detect.

The station in orbit is pretty safe actually. You can use it as a launching point for ships headed out from earth and they will get a good boost, but the station itself will not 'come down' any more readily than a station without a cable. Obviously, if something grabs the cable and pulls it out of orbit you've got troubles. But that would take a lot of force. It's got to be a large station to anchor the cable and make the 'center of gravity' of the whole assembly rest in orbit. Hundreds of thousands, if not millions, of tons. There has even been talk of trying to capture an asteroid and use it as the counter-weight. That's a whole other mega-engineering project. We can worry about that after we've got at least one working cable... In the meantime we'll probably mine the moon for the bulk of the station material.

The issues of who would get to use it, and what it would be used for, are actually more serious than the engineering questions. It looks like we've got a material that can be strong enough to make the cable (Carbon nano-tubes). Everything else is known technology. But once it is built what effect will it have on the world? That's a very different problem than the technology.

[ October 09, 2002, 05:06: Message edited by: Baron Munchausen ]

Re: OT: About Space Elevators
 

Here is my problem with it. This cable needs to be what, 15 miles at the least? They plan to also put this thing on a floating platform in the ocean (for logisitical reasons to remove stress on the cable).

Suppose the platform gets caught in a hurricane, or even just a small squall.

I can see that big platform going "SQUEEEEAKKK SQUEEE-SQUEEAKKK!!" followed by one hell of a "POP! PING! SHSHHRHRHHHHRAAAATCH!" and then that cable is going to come down nice and fast and make one hell of a splash/dent (depending on location.)

Re: OT: About Space Elevators
 

Actually, it is more like 100,000kms long. You can learn a lot by just the FAQs posted at the website Baron posted. I still think something like this is far in the future...

[ October 09, 2002, 05:16: Message edited by: Captain Kwok ]

Re: OT: About Space Elevators
 

What nobody mentioned in terms of energy used to get stuff up to orbit:

The main principle of any elevator is that whenever you send stuff UP, you send an almost identical mass DOWN (minerals mined on the moon, things produced in orbit, etc etc.). In this case you have a ridiculous small amount of energy needed for propulsion to overcome inertia ...

Just my 1 or 2 cent ... *g*

Re: OT: About Space Elevators
 

The down ward trip could be used to generate electricty. I belive it is called 'Dynamic Braking"

Re: OT: About Space Elevators
 

My concern is what if they can't move it away from the hurricane in time.

A project like that is going to be measured in the hundreds of trillions price tag and with gov't buying, they'll make 2 and 3x the price.

I also think they will come up with a self-clibing mechanism to pull stuff up. Sure it's slower, but we can slap an italian sticker on it and say it's romantic.

Re: OT: About Space Elevators
 

The idea behind the design is that the weight is held slightly past geosynchronus orbit so that the weight has a tendancy to fly away from the planet. The cable stops this and holds it in tension. An object climbing the cable effectively pulls the cable down, but since the cable has more inertia than the object, the elevator moves much, much more than the cable does. The tendancy of the weight holding the cable to fly away means that the weight has a constant influx of inertia to resist the tug of elevators. This inertia is probably at the cost of Earth's rotational speed, since it has to come from somewhere...

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">The principles of orbital mechanics do say that you are correct, but the total mass of the cable system in relation to the earth means the amount of change in the earth's rotation will be so infinesimally small they will be practically unmeasurable. In relation to the effect of the moon and the friction of tidal effects it will be for practical purposes nonexsistant.

[ October 09, 2002, 14:30: Message edited by: geoschmo ]

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">The estimates on the website are in the tens of billions actually. The main hurdle is designing the ribbon itself. Once that is done and the system is up and running, it could very easily pay for itself in a short time.

Well the ground unit can be placed in areas of historically low storm activity. And it can be moved to an extent, if the ground station is a mobile one. I would imagine that in the event of a particularly nasty storm, the cable could simply be disconnected and "Reeled up" out of danger. The ground station would just need to batten down and ride it out then.

Geoschmo

Re: OT: About Space Elevators
 

So it's actually a great space kite

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Right, so all we have to watch out for are great space kite eating trees. http://forum.shrapnelgames.com/images/icons/icon10.gif

Re: OT: About Space Elevators
 

I don't think wind is a concern. The cable will be far stronger than any material we currently know. Disturbance of the anchor point is more of a concern. If the wind increases the stress on the anchor point then maybe it would be a problem. Very rough seas if it's a platform at sea, or earthquakes if it's on land, could damage the anchorage and break the link.

That's an interesting thought on 'reeling up' the cable to avoid ground problems. If the system is well balanced I suppose it would be possible to detach from the ground point for periods of time. It would be easier to do this if there was an 'intermediate' station only a few hundred miles up. A seperate cable from this station to the ground would be easier to 'reel up' than a portion of the whole 22,000 mile cable. The 'convenience' of going straight to geosynch orbit would be lost but maybe the other convenience from this multi-stage arrangement would be worth the change. Most uses would be for near-earth orbit at first anyway. Once you got into true orbit there would be plenty of leeway for fancy arrangements of cables and stations.

Now I'm having visions of a system of a web of giant cables all around the earth and cable cars running between all points like subways in a large city today. Come to think of it, if you have multiple geosynch stations linked by a 'perimeter' of cables you'd be released from the necessaity of the ground link. They'd hold each other in orbit. Hundreds of thousands of miles of cable would be required for this, though. http://forum.shrapnelgames.com/images/icons/icon7.gif Just don't let a huge system like that get out of synch with the earth! http://forum.shrapnelgames.com/images/icons/shock.gif

[ October 09, 2002, 16:17: Message edited by: Baron Munchausen ]

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">So I could buy myself a £50 ticket and scoot up a cable off the coast of Australia at 9am. Then I could zing around the Earth on a super-fast space cable car and scoot back down another cable in the North Sea in time for lunch the same day. (except that it would be midnight... yeesh, jet lag would be horrendous.)

Then I could spend 19 hours and £200 trying to get from one end of Britain to the other by train...

Re: OT: About Space Elevators
 

The purpose of the ground link isn't to keep the ribbon taut. The ribbon doesn't have to be rigid, just basically stationary. You can't let it move around too much or you get problems with harmonic vibrations on the line. That would cause wild gyrations in certain spots that could damage the cable and/or cause the climbers problems. Anyone see the video of "Galloping Girdy", the bridge that tore itself apart in the wind. That wasn't because of a tremendous wind, it was just a slightly more windy than normal day, but the frequency of the vibrations in the bridge tore itself apart. That's the concern with the wind for the space elevator. That sort of thing can be actively dampened for the ribbon, but that requires manipulation at the ends. So they have to be attached to base stations. That is the danger of wind.

I don't know if they have any plans to reel up the cable in emergency situations like this, but there is no reason why you couldn't do it all the way from the high orbit. An intermediary station would be an unnceccesary complication. You don't have to take up the entire length of the ribbon, jsut reel up 15 miles or whatever to get the bottom end above the weather. The only quetions would be the reel having sufficent torque to take up the mass of the entire length of the cable. But the reel will have to be able to handle the mass of the entire length of the cable anyway or you would never be able to get it down to the ground in the first place. The only way to set the elevator up is to launch the spool in the conventional way and then reel it down from orbit.

Geoschmo

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">You could also send packages from Tokyo at 8:00am, and they would arrive at the pacific coast of america by 5:00pm the previous day!

Re: OT: About Space Elevators
 

As long as they don't make you climb the cable in gym class.

Re: OT: About Space Elevators
 

If something like this gets built I can really see it become some sort of "Holy Grail" for those base jumping lunatics that climb tall buildings and parachute off of them.

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Oh, you want to know about jumping from space do you. Well, try this OT link

Re: OT: About Space Elevators
 

Ok, here is what space.com has to say about the space elevator...

http://www.space.com/businesstechnol..._020327-1.html

Re: OT: About Space Elevators
 

I was born on July 7th, 1969. Nine days later Apollo 11 was launched.

For the first time since I realised my poor eyesight was going to prevent my childhood dream of becoming an astronaut, I have a real hope of making it into space in my lifetime. Maybe by the time I retire, I can take a vacation on the moon, or at least stay a week in an orbital hotel.

This is really exciting stuff.

Geoschmo

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">I was just dramatizing a point about terrorism. As a high profile project, (actually another Wonder) the Space Elevator would attract some real nut balls.

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">I was just dramatizing a point about terrorism. As a high profile project, (actually another Wonder) the Space Elevator would attract some real nut balls.</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">And it's a valid point. The website Baron linked too even talked abou tit some. They are hoping that this would open up space to everyone and so it wouldn't be something one of the disenfranchised would want to attack. That may be a little pie in the sky, but ya' know. http://forum.shrapnelgames.com/images/icons/icon7.gif

Actually as remote as it is likely to be placed, it would be fairly safe. It not like a hijacked airliner would be able to sneak up on it if the nearest flightpath is thousands of miles away. But on the other hand it wouldn't take a fully loaded airliner to bring it down.

Geoschmo

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Actually, if you plan ahead a little bit, it would take a lot more than that to bring it down.

If its out of the way, you have lots of time to take the plane down. They also have a very small, probably invisible from a distance, target to hit, so there is a fair chance they'll miss anyways.

Say a plane does come along and cut the ribbon. You will lose less than 30,000 feet of cable. Probably a LOT less, since they'd probably have to use the base station to locate the cable.
How do you repair the system? Just unwind some more cable from the counterweight station, and you're back in business...
Then put some more spare cable on the next elevator going up.

Re: OT: About Space Elevators
 

A plane hitting the cable is going to do damage to the plane, but it's going to break the cable as well. The cable slicing through the plane and ramaining intact is just not going to happen. We can't even comprehend materials strong enough for something like that. By the time we can planes will be faster and made of stronger materials too, so the plane will still break the cable.

You aren't going to have thousands of miles of cable falling down though, and it's not going to wrap around the earth. If the cable is that long it could of course wrap around the earth, but that much cable wouldn't fall down.

While the cable may thousands or even tens of thousands of miles long, a break in the cable at above a couple hundred miles is not going to cause it to come crashing down. The reason is that at that length the mass of the cable itself will be enough to keep it in orbit. Remeber that this isn't like hanging a rope fom a branch of a tree. The cable isn't supported by the sattelite at the orbital end. The cable is in effect a sattelite itself.

A break anywhere in the lower couple hundred miles of cable would cause everything below that to plummet to the ground of course. And a couple hundred miles of cable is going to be a problem if it lands on something. But you can limit the risk by locating the ground end carefully.

The literature on the website Baron posted talks about putting the ground end on a mobile ocean platform, like what is used for deep ocean oil drilling. These aren't attached to the ocean floor. This sort of arangment could actually be moved to avoid low earth orbit sattelites and possible sever weather such as a hurricane.

EDIT: Something else I didn't consider, but the website mentions. Parts of the ribbon above a certain altitude falling down will burn up in the atmosphere. So actually you may not get more than 10 or 15 miles of ribbon on the ground, not the hundreds that I was thinking. And the ribbon is heavy in total, but streatched out any particular piece of it is very light. So as it falls that part that survives the trip through the upper atmosphere will be slowed by the lower atmosphere to around the speed of falling paper. You'd have a big cleanup job picking up miles of ribbon cable, but it won't have much physical impact even if it hits something on the ground.

Geoschmo

[ October 09, 2002, 13:13: Message edited by: geoschmo ]

Re: OT: About Space Elevators
 

or they could have several parallel runs, that are interlinked at several intervals. say there are three cable runs. elevator cars could attacth around all three, but would be stable if only two held up.

while that might sound a little sketchy, the real advantage would be having the interlinkings between cables, so you would never really lose any. some would go slack, and you would just have to pick it up from where its dangling, and splice it back in.

or you can just go with the "reel some more out" method, which is probably alot easier, and maybe cheaper. the only problem there, is if 30,000 feet of cable come crashing down on the base-station, and sink it into the ocean.

A small battlegroup of cruisers and a AWACS or three, should be fairly capable of keeping air traffic away from it. I can imagine a little (huge) oceanic platform where cargo liners (and maybe cruise ships) come to load and unload cargo, and you would not want a several tons of cable to come slamming down on this.

the real cruicial time to defend it, would be when the elevator car is under 30 or 70 thousand feet, and would be vulnerable to conventional aircraft attacks.

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">I don't think an military presence is necessary. And I think it will create a diplomatic incident if there is a military presence into something grand such as that.

Re: OT: About Space Elevators
 

why? its a significant economic interest, the corporation that owns it will be bringing in loads of money for their parent country. not only that, but it is a significant boon to space bourne interests. anyone that wants to use it to put payloads up, will have an interest in defending the thing.

I would sure think it prudent to be able to shoot down any unauthorized craft that strays within 50 miles of it.

im just waiting for the strong-man competitions where individuals try climbing the things into orbit.

Re: OT: About Space Elevators
 

"I don't think an military presence is necessary. And I think it will create a diplomatic incident if there is a military presence into something grand such as that."

Oh no, it's only the largest and most valuble target on the face of the planet. Why defend it? http://forum.shrapnelgames.com/images/icons/icon12.gif

Phoenix-D

Re: OT: About Space Elevators
 

What I want to know is how they are going to ground the darn thing. Electricly. Isn't there an electrical charge difference between earth's surface and high altitude? Sounds to me like this would be the Mother of all Lightning Rods!

Who needs terrorists when NATURE itself will take care of the problem. http://forum.shrapnelgames.com/images/icons/icon9.gif

Re: OT: About Space Elevators
 

Just being that tall would make it the mother of all lightning rods, to say nothing of all the interesting effects it might have on global weather (and vice versa).

However, planes can take direct hits from lightning and keep going; if the car is on the outside, or cleared before a storm, I don't think a hit would do THAT much.

Phoenix-D

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Heh, that's a good point. HOw to get stuff to/ from the floating platform? Boats, sure, but boats are slow. It would be quite ironic if something this high tech revitalised some older technologies like flying boats & airships.

Re: OT: About Space Elevators
 

Good point about the lightning, Taz.

MAybe they yould even use this power that comes down the cable, it just has to be strong enough. Thus you would not need to "ground" it, you channel the current into your battery.

Re: OT: About Space Elevators
 

D of the V: Man, that's one honkin battery your talking about!!! Do they even make batteries with that kind of capacity? CAN they even make batteries with that kind of capacity???? http://forum.shrapnelgames.com/images/icons/shock.gif http://forum.shrapnelgames.com/images/icons/shock.gif http://forum.shrapnelgames.com/images/icons/shock.gif

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Well, if memory serves me correctly, according to Dr Emmet Brown ot the Back to the Future series, a lightening strike supplies exactly 1.21 jiggerwatts of electricity, which happens to be the exact amount needed to send a sports car into the past. So you could actually go up the cable in Australia at 9 in the morning and come down in Europe at midday in 1955.

Seriously, I should think the cable would actually do away with lightning in the area altogether... As I understand it, lightning is when static electricity builds up at cloud level to such an extent that it has to find the route of least resistance to the ground.
With a permanent link between the ground and all levels of the atmosphere, (and I'm not sure but I think bucky carbon would be a pretty good conductor) surely the static would be constantly conducting itself to ground and so there would never be enough built up to form an arc (lightening). Ummm...

You can tell I haven't studied science in 10 years!

Re: OT: About Space Elevators
 

<font size="2" face="Verdana, Helvetica, sans-serif">Even better for powering the thing if you have a constant current.

Re: OT: About Space Elevators
 

Well, once again according to the Faq on the website that Baron linked to, the current flow from the electrical diferential would be negligable. They kind of skirt the lightening issue by simply saying the best way to avoid lighetning strikes is to have the cable in an area that has a low histroy of lightening activity. That doesn't really say though what happens if it is hit. http://forum.shrapnelgames.com/images/icons/icon10.gif

I guess the ribbon itself won't be used for powering the climbers as I thought originally. They are suggesting photo cells on the climbers and use a ground based laser aimed at the cells to power the motors on the way up and down.

Geoschmo

Re: OT: About Space Elevators
 

Anyone ever read a scifi book called "The Descent of Anansi" (or something like that)? Can't remember the author. It was pretty good anyway. It wasn't exactly about space elevators but at the end of the book they've got these two damaged spacecrafrt joined by miles and miles of ultra strong cable, and they use the difference in orbital speeds at different heights to come safely down into the atmosphere. Same principle that keeps the proposed elevator up, I think.

Re: OT: About Space Elevators
 

regarding the revival of old technologies to ferry cargo:

the russians had an old cold-war design for a landing craft / transport that was essentially a giant snubbed-winged jet with its engines on the front. it required very small amounts of lift, because it "flew" on a coushin of air a few (50) feet off the ground.

boeing (or LM, i cant remember) is reviving the project and is developing one that can fly further, faster, safer (and is bigger). it can also accend up to 20,000 feet (wich the russians couldnt, being mostly a landing craft) to fly with conventional air traffic and make use of existing commercial airports. The speed and low fuel consumption (less work to fly low on a cusion of air) is expected to cause a great deal of competition with existing freighters.

regarding high capacity batteries:

both the US and Russia have developed and used nuclear batteries. I would say that is pretty high capacity, though you probably cant re-charge them. if you dumped the electricity back into the power grid of whatever mini-city you had at the base station of the thing, they could probably use a good deal of it.

regarding nanotube conductivity:

it can have properties of either a conductor, or an insulator depending on how it is structured. there was a test that placed one nanotube inside another, and used the inner one to conduct electricity (by pumping electrons down the center of the tube) and the outer on as insulation. so to extrapolate a guess, i think they are all insulative, but if built right, you can shoot electrons through the tubes themselves. (regular conductivity means passing electrons from one atom to the next).

Re: OT: About Space Elevators
 

Talk about the static discharge is probably because of memories of the tether experiments with the shuttle. This was a deliberate attempt to generate electricity with a conducting cable. I believe carbon nano-tubes are non-conducting. I sure hope so. Given the amount of power that little cable on the shuttle created I'd expect absolutely awesome voltages on a space elevator cable since it would run right through the ionosphere and even the Van Allen radiation belts. If the earth's magnetic field doesn't rotate at exactly the same speed as the lithosphere and the cable conducts, you've just made the largest magnetic generator in history.

[ October 10, 2002, 19:48: Message edited by: Baron Munchausen ]

Re: OT: About Space Elevators
 

From the High Lift systems FAQ:
<font size="2" face="Verdana, Helvetica, sans-serif">The FAQ has a lot of answers, but very little detail for those answers. But apparently they have looked at the issue.