Scientist Sees Space Elevator in 15 Years

bofh31337 writes "Scientist Bradley C. Edwards, head of the space elevator project at the Institute for Scientific Research, thinks an elevator that climbs 62,000 miles into space could be operating in 15 years. He pegs the cost at $10 billion, a pittance compared with other space endeavors. 'It's not new physics--nothing new has to be discovered, nothing new has to be invented from scratch,' he says. 'If there are delays in budget or delays in whatever, it could stretch, but 15 years is a realistic estimate for when we could have one up.' NASA already has given more than $500,000 to study the idea, and Congress has earmarked $2.5 million more."

Comments

Amazingly

[Anonymous Coward]

He saw the space elevator by looking through a wormhole at a mirror 7.5 years from Earth.

I'd volunteer to be an elevator attendant

[Anonymous Coward]

for the chance to get out into space.

Re:I'd volunteer to be an elevator attendant

[Rei]

Have you read about what this system is like first?

Re:I'd volunteer to be an elevator attendant

[SEWilco]

Not a good idea.
Do you have any idea what would happen to your voice as you call out the floors?
400 floors per mile.

"it could stretch"

[Anonymous Coward]

It sure could. It sure could.

no god this can be appening!!!

[Anonymous Coward]

Who would stand Muzak for a 45 min ride.....

Re:no god this can be appening!!!

[zhenlin]

Yea, this is true. People can't be just standing around listening to elevator music for so long.

They should probably be seated, and treated to something like a view, or a meal, or a movie etc.

But the question is, when you're lifting a whole floor, what kind of new techniques do we have to develop for building and operating lifts?

15 years?

[bugnuts]

that'll be the wait after pressing the UP button.

Imagine the jerk that presses the "close door" button as you're running.

Re:15 years?

[Scaba]

Dude, just take the stairs. You kids are sooo lazy today...

Re:15 years?

[JPriest]

I predict people will drive flying cars to work by the 21st century.

Re:15 years?

[fred fleenblat]

Seriously though, it could take a while to travel 62000 miles, even at a pretty good pace. Let's say it can manage 100 miles an hour. That leaves 620 hours to get there, or over 25 days. If you've only got one cable, there's no way for a car coming down to pass another coming up, so it's one shot every 50 days which severely limits cargo capacity.

The solution? Make the elevator cars disposable. Then you can just keep loading them up and sending them on their way so long as the weight limit on the cable isn't exceeded. When they get to the top, fire a small rocket that sends it into the atmosphere to burn up or just let them pile up until you have enough to make a space station with.

Re:15 years?

[AndroidCat]

Or worse, that some kids had pressed all the floor buttons.

Re:15 years?

[mangu]

Make the elevator cars disposable.

Or make two, one "up", another "down". I once saw in a factory in Sweden an elevator system like this. It had a lot of one-person wooden cabins that ran non-stop in an endless loop, one side went up, the other down. People joked that, if you missed getting out in the last floor, you'd come down head first as the cabin turned around. Of course, those cabins hung from the cable so that they didn't get inverted at the top, but I never tried to check this.

Re:15 years?

[tomhudson]

Why should it be limited to 100 mph? Once you leave the lower atmosphere, you can accelerate at a decent rate. 1 day, max.

Then just go flying off the end and you're on your way to the moon. Or Mars. Screw LEO (Low Earth Orbit).

Re:15 years?

[slashfoxi]

I'm not so sure about that 62,000 miles figure. That's more than the circumferance of the earth.

Re:15 years?

[Have Blue]

Screw him, how about the guy who hit the button for every floor?

Re:15 years?

[GTsquirrel42]

Sounds kinda like a ski lift. I still don't see any way to get it to work with just the one ribbon....

Re:15 years?

[bugnuts]

You won't actually travel the whole 62k miles. You'll probably go to the highest orbits to toss out satellites or such. There is a lot of wasted cable.

Re:15 years?

[Rei]

First off, it's not nearly so simple. Since the space elevator is tapered (in fact, a non-tapered elevator is essentially impossible around Earth), there is a weak point near Earth; this is your bottleneck. As soon as a craft passes the bottleneck, you can launch another; with Edwards' design, that's every 3-4 days. The entire trip is about 8 days.

Edwards' proposal *is* an up-only design, which I complained about on the message board (getting people out of orbit, while easier than in, is still quite dangerous and uses significant fuel). You can't just fire a little rocket to get out of orbit there (although you could slowly decelerate things with ion drives; wouldn't be too great of a solution for people, though).

There are plenty of ways for elevators to pass each other at high speeds when you're past the bottleneck; there are even more if you ditch the "flat ribbon held with rollers" concept and go to a "mesh" design, which can be climbed with teeth from one side only and has better resiliancy . If you allow down-climbing elevators, and keep your elevator size small to enable fast launches, energy recovered can be transferred to up-climbers, cutting down on the energy expense for the up-climbers (which makes up most of the cost, since power beaming is quite inefficient).

Re:15 years?

[bugmenot]

It will be even worse if some stupid kid presses all the buttons after leaving the elevator.

Re:15 years?

[StarsAreAlsoFire]

I am curious: how do you calculate the weak point near Earth? Genuine question.

My thought sugguests that the point which is under the most strain is actually at geo-sync -- the 'balance point'.

Also, a minor point: the hard part really _IS_ getting into orbit. It would be _nice_ to come back using the same system (and if done correctly, as you say, very nice indeed) but, for the most part, once an object lets go of the tether, it will NEVER be allowed to get near it again. EVER! Because you would HAVE to attach to the tether at geo-sync orbit -- or at least geo-sync SPEEDS -- which as I would guess you know, but others may not have considered -- are NOT the same thing. I am not justifying poor design; rather I am stating that if simplicity states that the first design be a flat ribben roller design, so be it. Reduce the risk, make the first one a roller, and for the sake of the Gods above, make #2 allow for return trips!

Not that I would ever want to come back......

Re:15 years?

[double-oh three]

getting people out of orbit, while easier than in, is still quite dangerous and uses significant fuel

Really? How much fuel did SpaceShipOne use to land after it reached it's apex?

Re:15 years?

[derkaas]

Really? How much fuel did SpaceShipOne use to land after it reached it's apex?

Yeah, but SpaceShipOne was never in orbit.

Re:15 years?

[mdielmann]

Incidentally, this is exactly what Charles Sheffield proposed in the 70s. Very good book. The side benefit is that you have a fairly closed system. The only energy expense after startup is friction and the net (yes, net) load from earth.

Re:15 years?

[BerntB]

Edwards' proposal *is* an up-only design

The plans I've seen are to use the first elevator to build more elevators.

So build your up+down elevator as a second one -- and use the first elevator for making new elevators/satellite launching.

Re:15 years?

[dfeist]

I once had to calculate the required length in a competition, and while I don't remember the result, it's pretty long. If you require it to be one long cable, so no very big counterbalance, it has to be several times longer than from the earth's surface to the geostationary orbit (ca. 35000 km). But even if you have a great mass available as a counterbalance, you better put it far beyond the geostationary orbit, otherwise it will have to be very big. And it's a lot easier to make it from one long cable, since it will be hard do make a connection between the cable and the mass because of the extreme forces.

Re:15 years?

[eram]

It had a lot of one-person wooden cabins that ran non-stop in an endless loop, one side went up, the other down.

What you describe sounds like a paternoster lift.

Re:15 years?

[jsebrech]

there are even more if you ditch the "flat ribbon held with rollers" concept and go to a "mesh" design, which can be climbed with teeth from one side only and has better resiliancy

How would you do a "mesh" design that supports travel at 100kph, which is what the elevator should at least be able to do? I just don't see how you can keep the teeth from tearing themselves or the cable apart at those speeds.

Also, how are you so sure the flat ribbon isn't the strongest design for nanotubes? From what I've seen the ribbon is a latticework of bonded nanotubes. Punching holes in that would seem to reduce ribbon strength in my mind.

Currently they do one shuttle launch every 3 months, imagine being able to send up that every 3 to 4 days, just on a single elevator (and once you have one, more are really cheap to build). How is that not enough?

Re:15 years?

[stephanruby]

I saw this in Budapest ten years ago, but it probably wasn't a paternoster lift. The one I saw did indeed reverse the cabin, so it was probably a precursor to the paternoster, it looked really really old.

Re:15 years?

[WolfWithoutAClause]

Why should it be limited to 100 mph?

Power. It takes an incredibly large amount of power to climb 38000 km to geosynchronous orbit.

It's ~500 KW per tonne of elevator to go at 200km/h near to the ground, but weight gradually reduces as you get nearer to geosynchronous orbit, and away from the earth and the power scales down proportionately.

The problem is, you can't carry enough fuel to get to the top (unless you use nuclear, but that's heavy).

Brad Edwards plan involves using ground based lasers to power photovoltaic panels.

Re:15 years?

[h4rm0ny]

I once saw in a factory in Sweden an elevator system like this.

It's called a patternoster. We had one at a place I worked (UK) and each 'box' held two people. Coming back from lunch one time, I found a queue of 12/13 people waiting to ride up - solution, I stepped into the one that was just disappearing into the ground. Two boxes later, I rise up in front of the still 8/9 people queuing.

I don't know why but it was incredibly funny. I'm probably just childish. :p

Re:15 years?

[tomhudson]

Actually, if you've been following the literature, one of the problems they are having is that carbon fibres are conductive ... and there's a HUGE potential between the earth's surface and the sky (just look at any thunderstorm).

The skyhook would act like throwing a wrench across the positive and negative terminals of a car battery - zap/boom/need new battery and new wrench.

So we're looking at a combination of ceramics and carbon fibres, and a (pretty much) free ride in terms of power.

Re:15 years?

[Anonymous Coward]

There's, ahem, slight, difference in "space"shipone's 100km apex and tens of thousands of kilometers for geosynchronous orbit, just in case you didn't notice.

Re:15 years?

[Anonymous Coward]

Hardly off topic, a space elevator in 15 years? Yeah right We have not even gone back to the moon yet in 40 years. I am only pointing out that we have had overly optimistic predictions about the future more than once in the past.

Re:15 years?

[Anonymous Coward]

Are you trying to sound smart? Cuz you sound like an ignorant loud-mouth smartass with that comment. Go read some shit before spewing forth. Asshat.

Re:15 years?

[DuckDodgers]

Sheffield was a fantastic science fiction writer. That book was the first or second of his that I read. Thanks for mentioning it.

Re:15 years?

[Rei]

The weak point is nearest earth for three reasons.

One, the taper of the elevator already overcomes what would otherwise put an unbearable strain at GEO. However, unless your taper doesn't quite follow an exponential curve and undercuts it slightly, the payload capacity increases toward GEO just because you have a larger margin of error.

Two, Edwards deliberately thins the tether in lower altitudes to reduce wind resistance and other bad effects that could sever the elevator. Now, the elevators leave the troposphere relatively quickly, but it is one significant issue.

Three, having the elevator thicker toward GEO imposes notably smaller penalties on the designs than having it thick toward the extremities (which would stress GEO a lot more).

Re:15 years?

[Rei]

First off, wheels gripping and then releasing a ribbon will do their fair share of damage - in theory, with a clean tooth grab vs. a clean ribbon grab, equivalent damage.

A mesh is not "punching holes" in it. A mesh is simply having your tubes or bundles of tubes intersect at a very slight angle - a few degrees - thus forming very elongated diamonds-shapes of CNTs. Edwards calls on the ribbon to be held together by some sort of magical epoxy in addition to the normal VdW, which is pretty unreasonable. You're going to need actual physical inter-tube bonds.

But the biggest reason is redundancy. You *don't* want to "put all your eggs in one basket" with a single strand, and you don't want your source of "redundancy" to be VdW force. When a piece of debris impacts the ribbon, even a micrometerorite, it "explosively" rips out a chunk. The further separated and the more physically bonded intersections there are, the better you take damage. That is the main reason why a ribbon shape is bad.

I recommend a mesh instead of a hoytether, btw, because Hoyt's design carries a lot of extra mass baggage. There are also other designs than a basic mesh that aren't a full hoytether. The hoytether is an extreme example of reinforcement; a minimal case is simply to have two helical reinforcement lines moving in opposite directions around as many vertical strands as you want.

Re:15 years?

[reezle]

I think it was just a confusion of terms...

The weak point described means the point on the cable that is capable of bearing the least load (because it is thinest). You were correct that the middle of the cable is under the most stress (basically has the force of 1/2 the mass of the cable pulling in each direction at one gravity). It being under the most stress is why it's built the strongest. The weak points are at the ends where you don't need quite so much strength...

#1 thing not to say about a space elevator cable

[isomeme]

"it could stretch"

wow

[crayz]

A scientist who thinks nanotube tech will be good enough to make a space elevator two years from now? I had no idea we were anywhere near that close

Re:wow

[cmowire]

Apparently the major remaining problem is mass production of an approprately strong nanotube. You have to remember that this isn't fully nanotech, it's just a chemical arangement of carbon atoms, so it doesn't require all of the nano-crap that the nanotechnology people have been going along about for so long.

I mean, the thing is, chemical rockets will only take you so far. So it's money well spent, for what the potential benefits would be.

Re:wow

[Rei]

No, it's not the only problem remaining. There are a ton of nanotube problems left, and there's some doubt that they even attain the sort of >100GPa tensile strength that Edwards' design requires (one test measuring actual SWNTs put the strongest ones in the test at around 60GPa (MWNTs have tested higher, but they're not applicable due to mass)).

Then there's the "fiber" problem. Nanotube fibers are at best held together by Van der Waals force. Edwards proposes some sort of unexplained "nanotube epoxy" that is somehow supposed to be able to withstand these incredible tensile strengths which the tubes themselves, even in theory, can barely withstand. I don't buy it one bit. The best fibers made so far, held together by the same forces, achieve the sort of tensile strength you get from Kevlar. Longer tubes will help, but you'd need a *huge* improvement.

The epoxy concept is bunk. There is a concept which might work, however: pressure induced interlinking of carbon nanotubes. Basically, you swap out some of the stronger sp2 bonds for the weaker sp3 bonds, but it interlinks the tubes.

I have other problems with Edwards' design, too, but he has done an awful lot of well-reasoned calculations. I contributed a lot to the article on Wikipedia, so if you want to read more about space elevators, that's the place.

Re:wow

[snarkh]

Well, you have to think his statements are more than a bit self-serving.

Re:wow

[Rei]

Yeah... his paper really is good - he's done some really serious calculation work and investigation into what is currently out there. He just makes too many assumptions, and makes them too optimistic. You have to, to make a space elevator work. Perhaps some day we'll get those CNT strengths. But one should keep in mind that it may well not be possible under the laws of physics.

Re:wow

[snarkh]

The problem is that he might kill the concept by promising too much and delivering too little.

Re:wow

[doozer]

.... kill the concept by promising too much and delivering too little.

If that were possible, there would be no more software companies.

Re:wow

[Anonymous Coward]

I spent the last 3 years working on a PhD on nanotube fibres, composits and chemincal functionalisation.

So far, there is no prospect of actually preparing a material that has all those extraordinary properties people keep babbling about.

I single nanotube is strong, sure, but as soon as you try to make composite materials it gets messy.

Nanotubes have been discovered in 1991 and a little later people started experimenting with them as filler for composite materials.
Can you buy any products? No.
Why? Because it doesn't work very well.
You get about the same (small) effect if you use a mix of glas fibres and soot. For fibres, any classical carbon fibre has much better properties than any SWNT-fibre presented up to now.
The problem is that you can publish any crap you like as long as the article got the word "nanotube" in the title. It's the same as with nuclear fusion: people keep promising it since the 60ties and forty years and hundres of billions of euros later, they're about as far from the goal as ever.

Nanotubes are interesting: from the fundamental research point of view, they allow for the study of a 1-dimensional electron gas, for example.
They are long and some are good conductors, so we might see transparent, conducting composites one day.
They might be useful for nanoelectronics, or as electron emitters in flat screens.

But I'll bet that there will be no space elevator in my lifetime (and I intend to live VERY long).

Working elevators on Earth

[macrom]

You know, it's cool that "they" are going to spend billions on an elevator to space, but I think it would be cooler if they could keep all 4 elevators in my building working correctly. Nothing like getting stuck, or seeing the Schindler repairman come out twice a week. Maybe he could make good use of some research funds!

Re:Working elevators on Earth

[Anonymous Coward]

how is this insightful? it is, in fact, offtopic. mechanical elevators have nothing at all to do with space elevators except sharing a noun.

Re:Working elevators on Earth

[Anonymous Coward]

reminds me of the elevator in my dorms. If you jumped just right between floors, it would hit the emergency brakes and you'd be stuck... time to call the emergency phone guy.

on the other hand, that's why we had hot girls in the dorms.

Re:Working elevators on Earth

[Anonymous Coward]

Schindler's Lift. The horrors.

Re:Working elevators on Earth

[kidgenius]

Ah, you must be in the Manzanita dorms @ ASU. All 4 of those elevators are in the top 50 most serviced elevators for the company.

Re:Working elevators on Earth

[Anonymous Coward]

or seeing the Schindler repairman come out twice a week...

He's not carrying a list by any chance is he?

Re:Working elevators on Earth

[Anonymous Coward]

> He's not carrying a list by any chance is he?

Well, a checklist, yes.

Re:Working elevators on Earth

[91degrees]

Take the stairs! Get some exercise!

I mean a 4 elevator building can't be much more than 40 floors. Think how much weight you'll lose.

Kick Ass

[www.fuckingdie.com]

And you thought that the CN Tower was a long elevator ride. I wonder how long it would take to go that far into space in an elevator? Would there be in-elevator movies and food service?

Re:Kick Ass

[Carnildo]

And you thought that the CN Tower was a long elevator ride. I wonder how long it would take to go that far into space in an elevator? Would there be in-elevator movies and food service?

There would need to be. At any reasonable speed, you're looking at a 24 to 48 hour trip.

Re:Kick Ass

[Coneasfast]

And you thought that the CN Tower was a long elevator ride. I wonder how long it would take to go that far into space in an elevator? Would there be in-elevator movies and food service?

There would need to be. At any reasonable speed, you're looking at a 24 to 48 hour trip.

you can live without food or a movie for 24 hours? damn man, what's your secret.

there would need to be basic food, bathroom, and entertainment (to prevent people from going crazy) services.

would be similar to a plane flight.

Re:Kick Ass

[Anonymous Coward]

elevator music, 24-48hrs straight, small confined space, no bathroom, food. This could be used by the government to pursuade dissadents to talk.

No actually what I was thinking was, don't throw away that empty mountain dew bottle before you get on the elevator. You'll need it in an hour or two.

Re:Kick Ass

[l810c]

Their FAQ says it would be a week long trip. Guess it would be traveling at about 369 mph.

Re:Kick Ass

[ultranova]

One would think watching Earth grow smaller beneath you would be entertainment enough. Those who have seen it before can bring books. Or maybe read the instruction booklets on how to avoid explosive decompression...

Rule number one: "Don't open the window" means "Don't open the window!".

Rule number two: "Warning! Danger!" means "Warning! Danger!".

Rule number three: If you really can't be bothered to obey the "Spacesuits mandatory" signs, then go ahead and win a Darwin award.

Re:Kick Ass

[TheOnlyCoolTim]

It would probably be a while before people rode the elevator. The safety would have to be proven, they would have to design a livable elevator, and there might be some problems with spending too long in the Earth's radioactive belt.

Tim

Re:Kick Ass

[ArsSineArtificio]

One would think watching Earth grow smaller beneath you would be entertainment enough.

I think it would probably be a cloudy blur for most of the trip. Either you'd be in clouds, or you'd be looking down at them. Not much in the way of "hey, I can see my state from here!"

Re:Kick Ass

[Anonymous Coward]

Tell you what, if you can get me a ride on the space elevator, I'll bring my own portable DVD player and a couple bag lunches.

Re:Kick Ass

[Anonymous Coward]

One would think watching Earth grow smaller beneath you would be entertainment enough

That would mean that the cabin would have to have a glass floor... I'm not sure I like the sound of that...

Correct me if I'm wrong...

[kwishot]

We don't experience this problem *now* merely because we don't have any structure that tall, but if something of this magnitude was built, wouldn't the earths rotation have some sort of effect on this?

-shameless gmail request for a military man... kwishot xatx yahoo-

Re:Correct me if I'm wrong...

[sjwaste]

Yep, the article says the earth's rotation will keep the cable taut. Makes sense.

Re:Correct me if I'm wrong...

[cmowire]

Already taken into account. In fact, it relies on them. The endpoint is in geosynch orbit, where a orbiting satelite will hover over a specific point, to keep it properly tensioned.

Re:Correct me if I'm wrong...

[Anonymous Coward]

You might want to read the article... They are counting on using the earth's rotation to keep the elevator cable taut. "Spinning a ball on a string around your head" was the analogy they used.

Re:Correct me if I'm wrong...

[meckardt]

The MIDPOINT of the cable will be in geosynch orbit. This is at 32K miles. The remainder of the cable is outside of this, to counterbalance the pull of gravity on the lower portion of the cable.

Re:Correct me if I'm wrong...

[Scaba]

Ahh, but what happens when the Earth suddenly stops rotating?

Re:Correct me if I'm wrong...

[Eskarel]

Half the globe becomes a fiery wasteland and the other half freezes and we've got bigger problems?

Re:Correct me if I'm wrong...

[mangu]

Inertia blends everything on Earth's surface into a gray, featureless, pulp?

Re:Correct me if I'm wrong...

[Anonymous Coward]

Still not quite right. The center of gravity must be in geosynchronous orbit. Note that the center of gravity is different than the center of mass, because gravity decreases with increasing altitude. Above the earth's surface gravitational force is proportional to r^{-2}, where r is the distance from the center of the earth.
So the midpoint (center of mass) must be farther out.

Re:Correct me if I'm wrong...

[Rei]

Still not quite right. :) The center of mass is closer to earth than the midpoint, not further. Although I think that's what you meant to say.

Re:Correct me if I'm wrong...

[homer_ca]

Small problem with this. If you send a payload up the elevator without sending and equal mass down the elevator, you change the center of mass of the system. Every load you send up pulls down the top of the elevator a little bit. You'll either need to boost the top of the platform or you'll need a huge counterweight in orbit so the mass of payloads is negligible compared to the mass of the counterweight. I'm sure these guys know more physics than I do, so I really hope they have an answer for this small problem.

Re:Correct me if I'm wrong...

[Anonymous Coward]

funniest, dumbest thing I've read all day

thanks

Re:Correct me if I'm wrong...

[CrowScape]

Except the cable would be kept taught by the Earth's rotation, so the only thing you would need to do to boost the top of the platform is to remove the payload from the elevator, at any point, and let physics do the rest.

Re:Correct me if I'm wrong...

[Wolfrider]

Stop, Drop and ROLL, baby! (Everyone flies off)

"The goggles - they do NOSSING!"

Re:Correct me if I'm wrong...

[Anonymous Coward]

Einstein called. He wants his brain back. Seriously, the elevator is helped by the rotation of the earth.

Some cautions

[shawkin]

This is a high performance, high stress ribbon
This application has little room for error. Obviously.

Wear on carbon nanotube ribbons may be significant.
Carbon nanotube ribbons may be susceptible to significant deterioration from cosmic rays.
Micrometeor impacts may also be a problem.

If the ribbon fails, what do we do with 62,000 miles of ribbon?
Oh wait, we build a Beowulf cluster of Christmas wrapping stores.

And then there is the cost estimate.
Low.

Re:Some cautions

[jefe7777]

if the earth's diameter is ~8000miles, i don't think this ribbon cable is going to be ~8 times that.

can you imagine?

the distance to the moon is around 30 times the earth's diameter...the ribbon @62k miles would be almost a third.

like someone else already posted. i think it's just 62 miles.

not 62,0000 miles.

Re:Some cautions

[cmowire]

It'd be a bargan at ten times the price, I suspect.

I mean, the big thing is that a few million to really take a good look at it and answer these sorts of questions. Compared to the benefits from being able to get stuff to and from orbit for incredibly low costs, and the cool stuff that then becomes possible, that's small change.

Plus, if it doesn't work out, there's a few *other* teather systems that could work as acceptable substitutes, so I doubt the research would be entirely wasted.

Re:Some cautions

[ceejayoz]

Like someone else already posted, a 62 mile cable would fall right back down.

You have to have the cable go past geosynchronous orbit to counterbalance and keep the thing taut.

Re:Some cautions

[ebassi]

If the ribbon fails, what do we do with 62,000 miles of ribbon?

Given the size of the ribbon, and the fact that carbon nanotubes simply burn out re-entering in the atmosphere, this is a non-issue: the lower part of the severed "cable" would vaporize, the higher part would still be orbiting, attached to the counterweight.

The real question is: what happens when some kilo-miles worth of vaporized carbon nano-tube is released in the atmosphere? Is this stuff ecologically-compatible?

Re:Some cautions

[f.money]

Don't think it'd vaporize, but a paper thin sheet of carbon fluttering down isn't going to do a whole lot of damage. There are issues (what if there's an elevator on the thing when the ribbon breaks?), but the structure isn't really one of them.

jon

Re:Some cautions

[jefe7777]

ok, i rtfa.

it does state 62,000 miles.

I doubt this will ever happen in that fashion.

A continuous strand 8 times the diameter of the earth whipping around our planet, nearly a third of the way to the moon.

needless to say, i have my doubts.

Re:Some cautions

[Anonymous Coward]

Paper doesn't flutter in a near-vaccum. It comes screaming down like anything else.

Re:Some cautions

[Have Blue]

Do not taunt Happy Fun Ribbon.

Re:Some cautions

[Rei]

While I think the concept of getting a space elevator any time soon is far overblown - the nanotube tech just isn't there at all (and may prove to be impossible), the beaming tech is only partly there, and I think Edwards will have a lot more trouble and expense with the climbers than he's counting on (they're not only spacecraft, but they're a brand new type of spacecraft that stresses electric motors incredibly heavily).... I strongly support the research as well. Research in CNTs and other high tensile strength materials is A-OK in my books :) As is research in power beaming, better electric motors, etc....

Re:Some cautions

[ceejayoz]

It'd burn up in the atmosphere as it came down. Too thin to survive the heat of reentry.

Build at the North Pole --

[PollGuy]

Then RKO's master plan will come true!

As long as it's not an OTIS

[mr_don't]

Yeah, i wonder if it will have one of those burgundy phones for when it gets stuck...

Re:As long as it's not an OTIS

[jokach]

If its like the burgundy emergency phone in the elevator I have at work ... it won't work.

Re:As long as it's not an OTIS

[Anonymous Coward]

Yeah, i wonder if it will have one of those burgundy phones for when it gets stuck...

Nope, you just get a chute and a big friendly message over the emergency hatch saying something along the lines of "you are now at 590 km, see you at 0".

Re:As long as it's not an OTIS

[Maserati]

I've actually heard the emergency phone in my elevator ring. I answered, it was - obviously - a wrong number. The lady at the other end didn't want to believe she had called an elevator.. Tough for her, she had.

A space elevator will not happen in 15 years...

[exp(pi*sqrt(163))]

...and nor could it. We are nowhere near having the kinds of materials required and no plausible extrapolation of technological development over the last century points to such a thing being possible. This is even more implausible than Kurzweil's prediction of a singularity happening in the next few decades. Why is it that people who should know better are often the people who understand the least? And why do other people take any notice of them?

Re:A space elevator will not happen in 15 years...

[Neil Blender]

Maybe you should take him on at longbets.org.

Re:A space elevator will not happen in 15 years...

[phil reed]

We are nowhere near having the kinds of materials required

Better RTFA, and maybe do a little research. We are actually within a factor of two of having materials strong enough; anything after that becomes essentially an engineering problem.

Re:A space elevator will not happen in 15 years...

[Scaba]

Right, and man will never fly. Between your proof by assertion and your sig, you seem to have some pretty strong beliefs there, my friend. I think you need a healthy dose of skepticism.

Re:A space elevator will not happen in 15 years...

[ConceptJunkie]

I think there may very well be a space elevator. And better yet, I'd love to take a ride on it and meet God.

Clearly, you didn't RTFA, nor have you heard of all the related advances that are being made. Why is it that people who think they do know better often understand the least?

Re:A space elevator will not happen in 15 years...

[exp(pi*sqrt(163))]

I've read the article and I've read much more detailed studies. There is nothing new in that article whatsoever. The materials that are being discussed have been manufactured in tiny amounts by methods that do not scale to producing a string tens of thousands of miles long.

Note, I'm definitely not saying a space elevator is impossible. I'm just talking about the practical difficulties which extend well beyond political and financial problems.

Re:A space elevator will not happen in 15 years...

[exp(pi*sqrt(163))]

Do you have a PDA or some other way to maintain a diary over a long span of time? You should put my ID down in your diary 15 years hence and then we can meet again on /. to discuss the fine elevator that may or may not have been built using technology that may or may not have been built.

PS I already have a healthy dose of skepticism. Maybe you mean I need a healthy dose of gullibility.

Re:A space elevator will not happen in 15 years...

[ConceptJunkie]

Well, you're right about that. I was also surprised to see this headline, but I've also noticed that the pace of development in materials engineering seems to be increasing, maybe not like Moore's law, but I think we will see some radical changes in our lives in the next decade or two because of it.

I'm waiting for extremely high density batteries. I think that will revolutionize technology more than anything since the integrated circuit, and it seems to me (IANAME) that the developments in nano-materials will allow this.

However, I still think you are way overstating the odds that it won't happen in 15 years. Of course, this is a gut feeling based on nothing more than, well, gut feeling.

Re:A space elevator will not happen in 15 years...

[exp(pi*sqrt(163))]

Let be me more realistic. As I've stated it above I've given in a 0% chance. I'd give it something like a one in a million chance. There could be a lucky discovery of some incredibly strong materials. But I think that people severely underestimate how long 30-60,000 (depending on design) miles is. That's really, really long. 15 years is a short time outiside of computing.

I think you're right to pick out batteries as an important developing technology. Well, I'd generalize it to power. If power consumption can be reduced enough there are many alternative sources of power.

Re:A space elevator will not happen in 15 years...

[Rei]

When you said "factor of two", you clearly meant factor to mean "exponent" for a large base.

We're nowhere even remotely close to > 100GPa; we're so far off, it's painful.

The best we can currently do on any sort of measurable scale is synthesize diamond via CVD at a rate of millimeters per hour. CNTs, should they somehow prove to have better strength than the experiments thusfar have shown (at best 60GPa), would have to scale up without losing that strength (quite difficult, if not impossible)

Re:A space elevator will not happen in 15 years...

[tgibbs]

Carbon nanotubes are strong enough. They just aren't long enough. So what is needed is either a way of making nanotubes longer or a way of linking them together. If they are linked together side to side, the cross-links don't need to be nearly as strong as bonds within the nanotubes themselves. Making the nanotubes longer gives more length to fasten them together, and decreases the strength requirement for crosslinking. But standard nanotubes may be too slippery to link up in this way; they might have to be chemically modified to link them together.

Re:A space elevator will not happen in 15 years...

[Rei]

... and chemically modifying them replaces the sp2 bonds that give them their incredible strength. See the quandry? Plus, even the best SWNTs measured so far are only ~60 GPa tensile strength.

Where's the tower?

[Chatmag]

The story mentions the cable, and a platform, so what kind of a tower arrangement is it going to have?

At any rate, at 62 miles, the lawyers are going to be lining up first, for the "helluva whiplash" suits.

Re:Where's the tower?

[dmoore]

There's no tower. You put a big counterweight at the top. As long as the center of mass is in geosynchronous orbit, it supports itself.

Re:Where's the tower?

[Courageous]

You're assuming that 62,000 miles is a typo? It's not. If the thing comes down it will wrap around the world at like mach-20. TWICE. Helluva whiplash suit there, yeah.

C//

Re:Where's the tower?

[Toad-san]

Who says it'll all come down? Just the part earth-side of the break will drop, the rest will go outwards.

And the part coming down is going to drop _straight_ down, not wrap around anything at all .. just pile up in a big heap. And since the anchor site is offshore, it'll be underwater at that, easily salvaged (if you wanted to).

You haven't worked the physics of this thing out yet, have you?

Re:Where's the tower?

[Anonymous Coward]

Obligatory bad joke

80s bad joke: There is now tower, only Zuul.
90s bad joke: Do not try to build the tower. That's impossible. Simply tell yourself, "there is no tower"

Re:Where's the tower?

[UserGoogol]

There is no tower. You have the satellite going in a geostationary orbit over the earth, and you hang a cable from it. That's what holds it up.

Re:Where's the tower?

[cr0sh]

If it is coming straight down, all that mass is going to slam into the water - I wonder what kind of tidal motions that would set up, and how bad it would be for shoreline communities? I suppose it would depend on where it was situated - the further out from land, the more energy the wave will expend before it reaches land - but you wouldn't want it too far from shore, as you need to economically get people to the loading platform/dock...

Re:Where's the tower?

[EvanED]

Nah. A significant portion (probably anything above the tear) would go out into space. Much of the rest would burn up. Anything that would remain would have a thickness and weight and thus terminal velocity comperable to a long sheet of newsprint. So it wouldn't land with much force. And probably would all land in the waters near the base.

Re:Where's the tower?

[Anonymous Coward]

There is a tower, on the ground, that holds the cable. It's probably about 2km tall, from the last diagram I saw.

There's a counterweight on the end, and I bet it can move up/down slowly, in order to keep the ribbon pointed up relative to the tower.

Re:Where's the tower?

[EvanED]

The entire cable would only be ~60 tons (26 lb/mile). Most of that wouldn't reach the ground. Any that did would hit pretty slowly; it would have a terminal velocity roughly that of a piece of newsprint with the same dimensions.

Re:Where's the tower?

[Rei]

About as much mass as if you dropped a non-coiled string into the water. It's about as dense...

In short, almost nothing. Not to mention that most of it burns up...

Re:Where's the tower?

[NoMoreNicksLeft]

With all the force of fluttering newspaper. It would take hours to come down, and would be more of a pollution problem than a catastrophe. Of course, this assumes failure at the thickest portion of the cable, just around geosync somewhere. The thinnest part, most likely to fail I'd think, if it were to fail, would leave it hovering just above the ground waiting to be duct taped back in place.

If there is a catastrophe to be had here, I'd think, it would be it burning (do nanotubes burn very well?). What sort of electrical storms are there that far up? The electrical potential between sky and ground can be huge, and we're stretching a non-insulator across the two.

Re:Where's the tower?

[jridley]

Has there been any proposal to take advantage of the electrical difference along the elevator? I'd think there'd be enough juice to run the thing for free if we could tap it.

Re:Where's the tower?

[DeeBs]

Carbon fibres eh? Can anyone say "worlds largest incandescent bulb"?

Re:Where's the tower?

[WhiteDeath]

The electrical potential between sky and ground can be huge, and we're stretching a non-insulator across the two.

is this where I recharge my electric car?

I wonder if there's a practical application for all that potential.....

Re:Where's the tower?

[jayrtfm]

>>>would be more of a pollution problem than a catastrophe.

umnn, and what happens when the super strong ribbon wraps around an oil supertanker's propeller/diveshaft?

Re:Where's the tower?

[Anonymous Coward]

What bollocks. Your talking about an immensely strong strip of lightweight material, stretched taut by enormous forces. Every drop a piece of rope on the ground? Lands nice and neat, eh? Every see a line on a sailing ship snap? That baby goes hawsering around the place, whipping people clean in two. The dynamics of scale cannot be ignored here. Wherever it comes down, its gonna leave a nice, neat slice several meters deep, and with the length we're talking about, you could wrap it round the earth several times, so expect it to be a problem for years to come, as it falls. Not to mention the fact that all the attached bits have to go somewhere too.

Re:Where's the tower?

[Smidge204]

The boat would probably break a driveshaft if the ribbon didn't break first.

But then again, what would an oil supertanker be doing anywhere within a thousand miles of the anchor site?
=Smidge=

Re:Where's the tower?

[EvanED]

But you're also talking about a strip that has a terminal velocity about equal to that of a newspaper page. It'd slow down to that speed *long* before it hits the ground. Remember, it's so long, so it also has a really long way to fall (and hence a lot of time to slow down) before it hits the ground. You would almost certainly see damage only at the anchor station, if even there.

Re:Where's the tower?

[Anonymous Coward]

Terminal velocity is the same for a cannonball as it is for a piece of newspaper, dang them laws of physics... You'd be talking about atmospheric drag, eh? Nope, can't see there being a lot of that on a stronger than steel ribbon stretching 60,000 miles.

Re:Where's the tower?

[wass]

The electrical potential between sky and ground can be huge, and we're stretching a non-insulator across the two.

Not true, that depends on the chirality of the nanotubes. Some chiralities are insulating, some are metallic. To boot, ropes of nanotubes have been measured to be superconducting at low enough temperatures.

Re:Where's the tower?

[EvanED]

Terminal velocity is the same for a cannonball as it is for a piece of newspaper

Um, no it isn't. In a vacuum (where terminal velocity doesn't really make sense anyway) they would go the same speed, but in an atmosphere (which our planet has if you hadn't noticed) terminal velocity very much differs. Or are you suggesting that if you drop a cannonball and newspaper from an airplane they will reach the same speeds. Terminal velocity is the speed at which the atmospheric drag balances the weight of the object.

Re:Where's the tower?

[NoMoreNicksLeft]

The arab-looking guy said he only wanted to learn how to pilot the boat, not dock it...

Re:Where's the tower?

[roystgnr]

With all the force of fluttering newspaper. It would take hours to come down, and would be more of a pollution problem than a catastrophe.

Not even much of a pollution problem if it was buckytubes - mostly CO2, and in a sense it would just be returning carbon that we'd already removed from the biosphere to create the tower in the first place.

The thinnest part, most likely to fail I'd think,

The ground end wouldn't be any more likely to fail because it's thinner - the reason it's thinner is that it wouldn't have to withstand as much tension. It would probably be more likely to fail due to sabotage, though, and possibly just because the lower section has to deal with Van Allen radiation and the lowest section has to deal with weather.

if it were to fail, would leave it hovering just above the ground waiting to be duct taped back in place.

For the elevator to work, the thinnest part has to be in more tension than the weight of the heavest payload you want to lift at once. Take away this tension, and the elevator won't just stay in one place, it'll rise (at first) and probably go into an elliptical orbit. It wouldn't do anything bad to Earth, but as long as it was no longer in an easily predictable (and even manually adjustable) location then it would be a big piece of space junk as far as other satellites are concerned.

Re:Where's the tower?

[jayrtfm]

>>what would an oil supertanker be doing anywhere within a thousand miles of the anchor site

maybe because ISR's plans only call for it to be 400 miles away from the shipping lanes? And the ribbon can drift a long ways when it is dropped from 100,000 feet

Re:Where's the tower?

[Anonymous Coward]

I think it was da Vinci that dropped a pea and a cannonball off the leaning tower, to demonstrate they both hit the ground at the same time. Terminal velocity is the maximum speed anything can reach due to gravitational pull. Whether this is offset by drag is a different matter. How much drag, I repeat, is there going to be on a thin strip of metallic ribbon thousands of miles long? Oh and by the way, we aren't talking about a newspaper here slick, we're talking about the combined weight of the newsprint for a week in New York state. Dynamics of scale, baby, gotta love em.

Re:Where's the tower?

[RoboRay]

I bet it would make one hell of a paper-cut.

Re:Where's the tower?

[EvanED]

I think it was da Vinci that dropped a pea and a cannonball off the leaning tower, to demonstrate they both hit the ground at the same time. Terminal velocity is the maximum speed anything can reach due to gravitational pull. Whether this is offset by drag is a different matter.

I quote Halliday, Resnick, and Walker:

When a blunt body falls from rest through air, the drag force D is directed upward; its magnitude gradually increases from zero as the speed of the body increases. This upward force D opposes the downward gravitiational force F_g on the body. We can relate these forces to the body's acceleration by...
D - F_g = ma ... if the body falls long enough, D eventually equals F_g. From [the above equation] this means that a=0 and so the body's speed no longer increases. The body then falls at a constant speed, called the terminal speed v_t.

(HRW, p. 104; emphesis in original, vector symbols over D and F_g omitted)

In other words, the terminal velocity (same as terminal speed; the latter is more technically correct since terminal velocity is a scalar not a vector, but I'm going with the popular term) is the maximum speed attainable CONSIDERING DRAG.

Think about it. Otherwise, the terminal velocity of EVERYTHING would be 299,792,458 m/s because you can accelerate anything to arbitrarily close to that speed given enough energy.

The Galileo (not da Vinci) experiment worked because the cannonball and pea both experince relatively little drag. You CANNOT tell me that if you drop a cannonball and newspaper off of the leaning tower of Pisa they will land at the same time.

How much drag, I repeat, is there going to be on a thin strip of metallic ribbon thousands of miles long?

Once it enters the atmosphere, a hell of a lot.

Oh and by the way, we aren't talking about a newspaper here slick, we're talking about the combined weight of the newsprint for a week in New York state. Dynamics of scale, baby, gotta love em.

Again, I realize this. However, if you streach out newsprint to that height (assume it doesn't tear), are you saying that it'll snap around the world a few times and decimate anything it hits? Because apart from the (significant) matter of strength, they would have approximately the same dynamics.

Re:Where's the tower?

[Anonymous Coward]

YHBT HAND :p

Re:Where's the tower?

[EvanED]

I suspected as much, and in fact was probably not going to go beyond one more message. But I don't really care. If it helps someone else, very good. If not, it was a waste of 15 minutes that I would have spent not doing anything of importance anyway.

Re:Where's the tower?

[Anonymous Coward]

Every drop a piece
Every see a line

"Ever".

And most of the cable will burn up in the atmosphere.

Re:Where's the tower?

[amorsen]

Ok, the cable broke, killing everyone on board the elevator climbers. And you're worried that a ship might lose a propeller. Right.

Re:Where's the tower?

[jsebrech]

it'll rise (at first) and probably go into an elliptical orbit.

What would make it stop rising? It's already going faster than escape velocity for the altitude, and there's nothing to slow it down. It seems to me it would just keep going.

Re:Where's the tower?

[whitis]

There are two theories: one that terminal velocity would limit the speed and the other that it would come down like a whip. I think both are true to an extent.

In the short term, terminal velocity would not apply since terminal velocity assumes that the only accellerating force is gravity. The tension of the cable would, however, be expected to accelerate the cable to supersonic speeds.

In the long term, drag would eventually slow the cable down to terminal velocity and/or cause it to burn up. A big advantage of the nanotubes is that they keep the weight to surface area ratio low, as does giving the cable a flat rather than round profile. Also, I assume they have very low stretch which would minimize the duration of accelleration.

The lower portion will not come down like a fluttering newspaper. It will have the tremendous tension accellerating it and it would have weight of its long length encouraging it to fall down lengthwise for minimum drag. Compare the drag if you were to hold a newspaper out the sunroof of a car perpendicular to the line of travel (holding all 4 corners) vs if you were just to hold two corners.

When you double the height of the break (assuming we are dealing with a section of uniform thickness), you double the mass, double the acceleration time, halve the acceleration (because the tension has twice as much mass to accelerate), and double the drag. These factors have a tendancy to cancel out. Also, portions high above the tower will take long enough to come down that they will tend to burn through. The most dangerous place to break the cable may actually be pretty close to the ground so that the time it takes the free end to hit the ground is not substantially longer than the duration of tension induced accelleation. The most dangerous portion of the cable may well be the length just slightly longer than the tower which the tower itself will cause to snap like a whip. In one sense, the tower makes it more dangerous that way. However, the reasoning behind the tower may be that the time it would take for the first part of the cable to hit the ground would be much longer than the duration of tension driven acceleration.

The cable may have low mass per unit length (like a piece of string) but a piece of string accelerated to supersonic speeds will cut. A ribbon will have more drag but could hit you edge on making it sharper than a string. In this case, we appear to be talking about a glorified piece of tinsel. Without the stored energy due to tension and stretch, it will be harmless kinetically; if the stretch energy is low enough it will still be harmless.

I would think that before deploying such a system you would want to do a pull test (even horizontally) to destruction of a mile long section of cable. You could test smaller sections but they

Any destruction, therefore, should be concentrated at the base station. It is possible that the stretch of the cable is so low that the stored energy in the system due to tension is not significant compared to the effect of drag that there isn't even much risk to the base station.

It looks like the space elevator will not have the amplifying effect in terms of destruction that would make it so appealing to terrorists. The best way to take out the cable would probably be two rockets with a cable stretched in (a modern day version of the chain shot used to take out the mast of a ship) because it is too narrow a target to take out with a conventional missle. However, it may well turn out that the two missles are a greater destructive force than the elevators cable they unleash. No, what makes it appealing to terrorists is its economic amplification and symbolic status. Anytime you can take out a multibillion dollar target with a thousands of dollars worth of missles, it is a good strategic investment to do so. That being the case, one of the costs of the elevator is going to be the cost of having the navy patrol the area and the opportunity cost of making a large chunk of ocean off limits.

Re:Where's the tower?

[jayrtfm]

Why would any deaths occur? The man rated climbers would have parachutes and heat shields.
The ship propeller problem is not my idea, it was brought up at last year's space elevator conference.
Since current treaties require the country of origin to be responsible for damage caused by anything which falls out of space, these sorts of issues may prevent goverment approval of the elevator.

Re:Where's the tower?

[TheMadReaper]

> The thinnest part, most likely to fail I'd think,
> if it were to fail, would leave it hovering just
> above the ground waiting to be duct taped back in > place.

This is not true, the base of the elevator has to be in tension so if you try to climb the elevator the elevator pull you up, rather than you pulling you down. Therefore, if the base of the elevator breaks, the base will go snapping upwards.

Re:Where's the tower?

[Courageous]

Where'd you get this figure?

C//

Re:Where's the tower?

[Courageous]

It will have the tremendous tension accellerating it and it would have weight of its long length encouraging it to fall down lengthwise for minimum drag.

Half way up, at 32,000 miles, there is no appreciable drag. Also, I question your mass-density assumptions.

. In this case, we appear to be talking about a glorified piece of tinsel.

Upon what are you basing your assumptions of its width and overall mass per unit of width-length?

Any destruction, therefore, should be concentrated at the base station.

I personally doubt your premises, so am therefore naturally having some difficulty with the conclusion. :)

Re:Where's the tower?

[NoMoreNicksLeft]

True, but the center of gravity of the whole thing is still roughly in geosync orbit... so it stays put, on a relative scale. The snap upward could be anything from inches on up to a few hundred yards, I would think. It doesn't get flung to Jupiter. People would scramble to re-anchor it, and you can't minimize the urgency or difficulty of that, but you aren't starting over from scratch, either.

Re:Where's the tower?

[whitis]

Half way up, at 32,000 miles, there is no appreciable drag. Also, I question your mass-density assumptions.

Once that portion enters the earths atmosphere, however, it will begin decelerating and disintegrating and will have plenty of time to do so before it can hit objects on the ground.

Upon what are you basing your assumptions of its width and overall mass per unit of width-length?

Well, according to the documentation the nanotubes have a density lower then kevlar, and the lower portion is 2CM wide by 5 microns thick. Now, if they goop the nanotubes up with epoxy, that could affect the density by a little bit (they don't plan to use much). With just the nanotubes, we are looking at a weight of 130grams per kilometer of cable (0.02M * 0.000005M * 1000M *1300 Kg/M^3 = 0.130Kg). For comparison, I just measured a piece of reynolds heavy duty aluminum foil at around 0.5 mils (12.7 microns). So, one food service roll (18"x500foot) could be cut into 22 ribbons and welded end to end to make 3.3Km of cable (at 2-3 times the thickness) and more than twice the density (2700 Kg/M^3). So, your aluminum replica will be about 5 times as heavy and (very roughly) 1000 times weaker than 3.3Km of nanotube cable. The tensile string of the nanotubes is 130GPa (19 million psi). The entire 91000KM length of cable will weigh roughly 18000 Kg, or about as much as 20 automobiles. If 1 km of the ribbon hits you at the speed of sound the force of impact (44.2 kg m/s) would be the equivalent of a 98 pound weakling bumping into you at a slow walk (2.2mph). But you might get one hell of a paper cut.

Their worst case estimate for how long a segment of cable could fall to earth without disintegrating is about 4000km or 3000kg (about the weight of two SUVs). That density is different that what I discussed above because we are talking about a higher strength cable. It looks like the figures I was looking at were for the cable before it has been beefed up by the maintenence droids. Now, I don't want a hummer landing on my head but it doesn't sound any worse than a stray rocket.

Re:Where's the tower?

[Courageous]

Well that's all very interesting. The last time I looked at this subject, the stated requirements for strength required many, many times per unit of mass strength. Somewhere, the estimation of the strength of carbon nanofiber must have increased by orders of magnitude.

C//

Re:Where's the tower?

[amorsen]

It would be pretty hard to save people stuck above the breaking point. Not impossible maybe, but pretty hard. Either way, concern about a remote possibility of damage to shipping seems rather silly when current methods of getting people into space kill so (relatively) many.

Re:Where's the tower?

[jayrtfm]

>>concern about a remote possibility of damage to shipping

This is exactly one of the issues that the EPA required to be addressed in the environmental impact statement that was required to get the launch liscense for SpaceShipOne

Re:Where's the tower?

[roystgnr]

It's already going faster than escape velocity for the altitude,

The reason I said "probably" is because making statements like this one is so hard. When talking about something tens of thousands of kilometers long, it's hard to say that "it" is doing anything, and if the tether is not tethered down nicely then even the basic behavior turns from a tractable statics problem into a hideous dynamics problem.

If the tether is using a large counterweight just past GEO (the initial tether strand won't, but later additions probably will) rather than a small counterweight far past GEO, then there's no reason why any part of the tether needs to be going faster than orbital velocity for its altitude, in which case it would still be stuck in Earth orbit no matter where it's severed.

If the tether is being used for interplanetary launches without large rocket stages, then it will need to extend far enough that its tip will be going faster than escape velocity, but this tip will be outweighed by the section near GEO - for it to leave Earth orbit, you'd have to sever it high enough up that there's not too much of the lower-velocity section weighing it down.

We've spent money for worse...

[sjwaste]

At the minimum, keep this guy funded so he can research the necessary materials. The article gives a timeframe of 2 yrs for the nanotube technology. If something like this could actually be built in the coming generation, getting things into space will probably become a whole lot cheaper.

Plus, a space elevator.. it even SOUNDS cool. Almost as cool as moonbase.

Re:We've spent money for worse...

[dilettante]

Yeah, but the problem is that the reds will just blow the darn thing up and it'll wrap itself around the planet a couple of times killing everything in its path. Oh, no, wait, that's on Mars. Never mind.

No new news

[Michael Crutcher]

This is the same story that's been going around for a while, there is no new news in the linked article.

The current issue of Discover magizine has a much longer and more informative writeup.

Re:No new news

[EvanED]

I'll second the (July 04) Discover article, a summary of which is at their site. A full version may go up online in July. Quite the informative bit of work. It went a long way to convincing me it might be a good idea.

Re:No new news

[pnatural]

Ah, but it's news to ./ story submitters and editors because it's the headline right now on Drudge Report.

I've noticed a trend over the last 12 months... more and more stories show up on slashdot within hours of appearing on drudge. Sad.

Re:No new news

[mblase]

This is true; it isn't new news. However, this is the first time I've seen the space elevator concept in an AP newswire article. This same story made page 2 in my city's newspaper, which means it's the first time many Americans will have heard of it, let alone learned it's feasible. That means, with any luck, it's also more likely to reach the ears of the executive branch and receive favorable funding.

2 years to work out nanotube materials???

[Anonymous Coward]

Give me a break. 2 Years? It could be 15 years just to develop a commercial process for the nanotube materials.

There wont be any space elevator anytime soon.

Phil Condit
Boeing

Re:2 years to work out nanotube materials???

[Anonymous Coward]

Phil Condit
Boeing

Dear Mr. Condit,

You do not work at Boeing anymore. Please do not attempt to enter the premises or you will be arrested.

Sincerely,

Boeing Security.

In Space...

[Zorilla]

...Nobody but you can hear the elevator music

And consequently, nobody can hear you scream.

Re:In Space...

[cipher uk]

actually the other people in the elevator can. it will have air in there which can vibrate :). (unless everyone wheres air masks) so they can hear you scream and the annoyance from it may cause them to throw you out the door ^.^

Re:How Far?

[TehHustler]

And I think he means 62,000 miles. 62 Miles is only the boundary of space. What would the point of finishing there be? The reason he says 62,000 is because it covers everything useful in space travel, from Low earth orbit up past geosynchronous orbit.

He has to justify his $500,000.

[Beardo the Bearded]

Here's what could have happened:

Edwards: "Nope, it'll never work."

NASA: "No more cheques for you, then."

Edwards: "B'oh."

Re:He has to justify his $500,000.

[exp(pi*sqrt(163))]

Damn! I keep doing this. Sorry. I shall write on the board 100 times "I will not blow the whistle on scams that are in the interest of me and my fellow /.ers". I want this 15 year prediction to be true and maybe if we let this guy speak his lie it will help make it come true in 50-100 years time.

Arthur C. Clarke

[Anonymous Coward]

Nice little read on such an invention in Clarke's 4th book in his Odyssey quadrilogy- 3001: Final Odyssey. If you're interested in this at all, read the book.

Re:Arthur C. Clarke

[Anonymous Coward]

Arthur C. Clarke is like L. Ron Hubbard without the religion. He currently lives in Nepal with a harem of young boys. His one-page paper on geo-stationary sattelites wasn't the first such paper, nor did it have anything to do with later research on geo-stationary sattelites, still he self-promotes himself like the father of weather-satellites.

His "space elevator" idea was occupied skyscaper-buildings made of diamonds, so tall they go all the way into space. Entirely different than a ribbon leading into space.

3001 is without a doubt one of the stupidest books ever written. Nothing but an excuse for him to rant about how barbaric all his pet peeves are - he doesn't like circumcision or the word "God," amongst other things.

Re:Arthur C. Clarke

[TheGavster]

Also good on nanotube elevators is Kim Stanley Robinson's [red/green/blue] Mars triology. He even addresses a bit of the issue of the thing falling over (though his is substantially heavier than this proposal, and only reaches to geosynch rather than going out past geosynch for balance)

The submitter stole the headline

[Anonymous Coward]

The submitter obviously saw this on Drudge Report, swiped the headline and link, and submitted it to Slashdot. It was "Scientist Sees Space Elevator in 15 Years" over there too, top headline.

Correct.

[LuckyStarr]

You must calculate the angle and the length of the ribbon (the position and mass of the counterweight) to even out the centripetal force of the earths gravitation. I can not calculate these for myself but I am sure there are people out there who can. :)

However

[Anonymous Coward]

Does it have Celine Dion elevator music? If so, fuck it.

Re:How Far?

[sirenbrian]

No, it *is* 62000 miles. The tether has to be that long to allow a suitable anchor to be attached at the other end and keep the right amount of tension on it. Or something. /not rocket scientist, but mightily impressed at this bloody good idea.

Re:How Far?

[TheKidWho]

No he definetly means 62,000 miles, at 62miles high the thing would plumit back down into the earth unless you ahd rockets constantly going on the top of the thing.

Radiation

[mikejz84]

One little problem for a human to ride the space elevator--the slow speed of assent means that people would pass though the Van Allen belt for a rather long time--exposing them to possibly deadly radiation.

Re:Radiation

[cmowire]

Radiation shielding is a well-understood problem. It just takes some extra mass.

Re:Radiation

[Carnildo]

One little problem for a human to ride the space elevator--the slow speed of assent means that people would pass though the Van Allen belt for a rather long time--exposing them to possibly deadly radiation.

Relatively slow. Once you get out of the atmosphere, speeds of a thousand miles an hour are not unreasonable.

Re:Radiation

[Anonymous Coward]

thousand miles an hour? Screw the elevator, they should be making world's largest rollor coaster!

Re:Radiation

[cr0sh]

Once you have the elevator, make water part of the mass, and shielding all in one go - once at the platform, it could be stored for later processing into fuel, or use it for drinking, or space-based agriculture...

Re:Radiation

[Deanasc]

people would pass though the Van Allen belt for a rather long time

Yeah but then you get to stretch your arms out and watch your girlfriend catch fire.

I am so old school geek!

Re:Radiation

[Man of E]

And when they're not in the Van Allen belt, the elevator speakers are playing Van Halen, which is at least equally deadly.

Re:Radiation

[Anonymous Coward]

...the slow speed of assent means that people would pass though the Van Allen belt...

No, the (real) slow speed of assent means that 15 years is an overly optimistic estimate of a space elevator construction timetable.

The (theoretical) slow speed of ascent may mean some increased radiation for a passenger, but who cares? I'm on a space elevator, Ma!

;)

Re:Radiation

[amembleton]

Wikipedia has a good explanation on 'The Van Allen Belt's Impact on the space elevator'.

Re:Radiation

[Anonymous Coward]

I think you mean watch her turn invisible.

I'm older school geek.

Re:Radiation

[Anonymous Cowtard]

Um... Mr. Fantastic's girlfriend went invisible. It was her brother that "caught fire". Unless there was a funky undertone to the story that I never caught about some forbidden male/male mutie love goin' on.

Re:Radiation

[craXORjack]

That's why they would have a guy standing at the top keep pushing the elevator button over and over. Because we all know that makes it get there faster.

Re:Radiation

[puppet10]

heh if you use water as shielding you can't exactly leave it at the top :)

Though you could bring down some wastewater for treatment on the surface.

Re:Radiation

[Anonymous Coward]

If the Van Allen radiation belts are a problem, why not get rid of them? If this were done, the Space Station could also be pushed into a higher orbit, where there's less atmospheric drag.

One big engineering project deserves another...

Re:Radiation

[scotch]

World's largest water bong.

Re:Radiation

[uberdave]

You wouldn't leave it at the top. Astronauts returning to home would need as much protection on the way down as they needed on the way up.

Re:Radiation

[Deanasc]

Alzheimers

Re:Radiation

[Anonymous Coward]

It is clear that you don't understand the problem. It isn't a matter of just adding some extra mass.

Re:Radiation

[Slashamatic]

The Van Allen belt contains by defintion charged particles (trapped by the Earth's geomagnetic field). This will just be lot of Alpha and Beta particles with some ions. Alpha is stopped by compartively small amounts of shielding (foil does well enough). Beta is more penetrating, but water could help that (it can also be easilty transferred to the downward elevator for bidirectional travel.

Big lumps of Lead is only vital when we are talking X-rays or Gamma. To be honest, with such a long ascent, probably solar flares would be more dangerous (and these do give off X-rays at least).

Re:Radiation

[KieranElby]

From the bottom of that article:

There is also a proposal by the late Bob Forward called HiVolt which may be a way to drain at least parts of the Van Allen belts to 1% of their natural level within a year.

Hmm. Is it just me, or does messing with the Earth's natural electromagnetic fields sound like a particularly bad idea?

Re:Radiation

[puppet10]

Thats what I was saying since the original poster suggested it was being left at the top.

I hope english is a secondary language for you.

"Nothing new"

[dj245]

nothing new has to be invented from scratch

While technically true, carbon nanotubes need to be much stronger and more developed before they can be employed in a space elevator with a good margin for safety.

How would this affect the economics?

[rueba]

I keep hearing that a space elevator would be the cheapest way to get stuff into space.

How much would it cost to get a pound(or kilo) into space using a space elevator compared with current technologies or the more conventional approaches competing for the X-prize?

Re:How would this affect the economics?

[Naffer]

I guess once you have a space elevator in place, the amount of energy required to lift a mass would be P.E.=mass(height). Thats a whole lot less then a rocket uses.

Re:How would this affect the economics?

[Maserati]

And you get most of that energy back when you bring a load back down.

Re:How would this affect the economics?

[rueba]

Thanks, but actually I was wondering if someone knew the actual dollars per pound numbers.

Well its all very speculative anyway.

I am not really convinced this will ever happen, but if it is built in my lifetime that would be pretty cool.

Re:How Far?

[Courageous]

You cannot achieve geosynchronous orbit at 62 miles. Hell, I'm not even sure you can even achieve fast orbit there...

C//

Arthur C. Clark

[isoprophlex]

Another Arthur C. Clark moment, he has come up with so many amazing inventions in his chronicles. The satellite, now this... Actually I'm not sure if he did come up with the idea, but it was in 3001. So if you want to read about the theories of space elevators. This is the book to pick up.

Re:Arthur C. Clark

[Poseidon88]

Well, "3001" wasn't published until 1996. He wrote "The Fountains of Paradise", another book about a space elevator, in 1978. But, at any rate, sci-fi authors rarely think up these things themselves. Instead, they generally get their ideas from journals and contacts in the scientific community. For example, one of my college CS professors is friends with Greg Bear, and helped him with background material for a couple novels.

Re:Arthur C. Clark

[TheFlyingGoat]

Try Fountains of Paradise, and only after you read the article. Nice try, though. :)

Re:Arthur C. Clark

[Anonymous Coward]

It may not have been the first. I think I read a SF book about the time Fountains of Paradise came out. I think it had "Spider" or something similar in the title, but it's been almost a quarter century since I read it. Perhaps someone else remembers it.

Re:Arthur C. Clark

[Anonymous Coward]

I did some more research on this and found the following:

The concept of the space elevator first appeared in 1895 when a Russian scientist named Konstantin Tsiolkovsky was inspired by the Eiffel Tower in Paris to consider a tower that reached all the way into space. He imagined placing a "celestial castle" at the end of a spindle-shaped cable, with the "castle" orbiting Earth in a geosynchronous orbit (i.e. the castle would remain over the same spot on Earth's surface). The tower would be built from the ground up to an altitude of 35,800 kilometers (geostationary orbit). Comments from Nikola Tesla are suggestive that he may have also conceived such a tower. His notes were sent behind the Iron Curtain after his death.

http://www.campusprogram.com/reference/en/wikipe di a/s/sp/space_elevator.html

Re:Arthur C. Clark

[bobroberts]

"The Web Between the Worlds" by Charles Sheffield

Re:Arthur C. Clark

[Anonymous Coward]

"The Web Between the Worlds" by Charles Sheffield

Thanks! That shows how the mind can play tricks on you, I associated "web" in the title with spiders.

I'm going to have to pick up the book again. Apparently it came out roughly the same time Arthur C. Clarke's book did, and I liked it when I was in junior high.

Re:Arthur C. Clark

[bobroberts]

You can pick up the ebook version on Baen's webscriptions site (www.webscription.net), that's where I found it. Good read.

Re:Arthur C. Clark

[Anonymous Coward]

Now if he'd been smart, as well as inventive, he'd have patented it. And also patented the same thing ".. with a computer" and "... via a network".

Re:Arthur C. Clark

[kerrbear]

He wrote "The Fountains of Paradise", another book about a space elevator, in 1978.

As I recall the "shaft" of the elevator was made with a special new material that has the strength of steel at the molecular level. I.e. a strand of it one molecule thick could not be broken and was also super dangerous as it could cut through almost anything.

Interesting concept, but I guess we don't really need that stuff after all...

Re:Arthur C. Clark

[GileadGreene]

Thank you for pointing this out. IMHO Tsiolkovsky doesn't get anywhere near enough credit for his genius. Not only did he come up with the idea of the space elevator, he did seminal work on the theory of rocketry (including developing what amounts to the most fundamental formula in propulsion, the "rocket equation": mf = mi*e^(-dv/[g*Isp]) ), developed a number of ideas about space stations, and came up with the idea of solar sails. All of this in the late 1800s, before heaver-than-air aircraft existed, let alone spacecraft. As always, the Wikipedia has more info.

Re:Arthur C. Clark

[Anonymous Coward]

Aren't you thinking about the stuff that was holding the solar blockers together on Ringworld?

Re:Arthur C. Clark

[blincoln]

This is the book to pick up

No, really, there is no reason to pick up 3001 at all unless you want to see the story from the previous three books completely trashed and diminished.

I told a friend once the basic premise (Frank Poole getting frozen in space for 1000 years) and he said something like "So it basically reads 'So... cold. So... very... very... cold. Fucking... computer.'"

Re:Arthur C. Clark

[Julz]

Also he wrote about it in "Fountains of Paradise". We can always hope that he will be around for the opening and first lift of the "Space Elevator".
I also eagerly await the "The Trigger" and "The Light of Other Days" (has been observed now) concepts to become reality.

Re:Arthur C. Clark

[timeOday]

The tower would be built from the ground up to an altitude of 35,800 kilometers (geostationary orbit).

I don't think this counts, it sounds more like the Tower of Babel than a space elevator.

Re:Arthur C. Clark

[juhaz]

It was diamond cable. Surprisingly close to the stuff we're trying to make it from...

Re:Arthur C. Clark

[medvezhatnik]

Yes, this guy was amazing even in Russa there are not many people who remember what this name was all about.
Anyway, if there will be a space elevator I want an elevator music in it!

Re:How Far?

[Tumbleweed]

Hell, man, that's *way* past geo (22,800miles?) - how far is it to the nearest LaGrange points? I'll hafta check, but I'm thinking way farther than that. What is out that far (but not near far enough for an L-point)? Hmm.

Ob. RD

[Anonymous Coward]

Welcome to Xpress Lifts, descent to floor sixteen. You will be going down two thousand, five hundred and sixty-seven floors and, for a small extra charge, you can enjoy the in-lift movie "Gone With the Wind." If you look to your right and to your left, you will notice there are no exits. In the highly unlikely event of the lift having to make a crash-landing, death is certain. Under your seats you will find a cassette for recording your last-minute testament, and from above your head a bag will drop containing sedatives and cyanide capsules.

We're almost there

[Trailer Trash]

He pegs the cost at $10 billion...NASA already has given more than $500,000 to study the idea, and Congress has earmarked $2.5 million more.

Wow, at this rate, we'll have the money in, oh, 1000 years...

Re:We're almost there

[geekanarchy]

The way the US government throws its money around, I see no problem with $10B. It recently approved at $417B defense bill. See here.

Heck, they'll likely build a matching pair of 'em just because they can.

one pitfall they didn't mention

[Anonymous Coward]

So I was on the Space Elevator last month, and 10 minutes into the ride a guy sitting next to me ripped one! "Sorry," he says, "I had spicy enchiladas for dinner last night." Longest trip of my life.

Re:one pitfall they didn't mention

[Anonymous Coward]

You're wearing spacesuits. They're individually sized so you won't have to wear his next trip, thank goodness.

Brings new meaning...

[lohmann]

...to getting stuck between floors. Stuck between atmospheres, maybe?

What are the obstacles?

[Anonymous Coward]

So what are the obstacles to getting this to work?

The longest nanotubes made so far are less than a millimeter. I suppose the first step is to figure out how to make them longer, and weave them into fibers.

Once this nanotube belt is assembled, how do we get it into space? Even if it is thinner than paper, it will still weight at least a few thousand tons. That is a lot of shuttle flights.

How does the elevator winch itself up the cable?

As for power, aren't nanotubes conductors? So could we use the cable itself to transmit power?

Re:What are the obstacles?

[cmowire]

That's actually worked out.

It's some reasonably small number of launches to send up a few strands, just enough to allow the climber to work.

From there, you start a climber on the base and send up more and more strands, until it's strong enough.

OK, then--call me back in 15 years...

[Art Tatum]

When he sees it.

Yikes

[Tumbleweed]

> At any reasonable speed, you're looking at a 24 to 48 hour trip

That's a _shitload_ of crappy muzak, there! Better bring a fully-loaded iPod.

And hope there's no crazy guy singing 'Roxanne' while you're in there.

Re:Yikes

[Anonymous Coward]

Might as well get some fun out of him.

"hey, all guys drink when he sings 'roxanne'"
"and the girls when he sings 'red light'"

I have heard bad stuff about vomit in zero-g,
but it cannot be as bad as 48 hours of muzak.

There is no tower.

[Anonymous Coward]

The platform is in a geostationary orbit. The elevator is only connected to the Earth via the cable.

If it helps, think of it as a space station with a long, tough rope hanging down all the way to the surface. Tie something to the bottom of the rope and all you have to do is haul it up. Bam! Space Elevator.

Re:There is no tower.

[Chatmag]

I kinda get it and then I don't.

The upper platform is held in orbit. By bringing an elevator up, don't you put an opposite pull on the platform, bringing it down? I guess I'm thinking centrifugal force here, that the upward pull would overcome centrifugal force, or would bringing it up work with centrifugal force rather than against it? Or is that even a factor?

Re:There is no tower.

[EvanED]

You'd just put enough counterweight at the end or the counterweight out far enough that it still wouldn't come back in.

Re:There is no tower.

[Chatmag]

Thanks for the clarification, I got it now.

*goes back to playing with my slinky in the corner, thinking, "this isn't much for a company game room"*

Re:There is no tower.

[NoMoreNicksLeft]

Anything past geosync pushes the other way, via centrifugal force. The trick is to have a substance strong enough to not get pulled in half.

How is this build?

[amacedo]

I really don't understand how this can be built!
I understand what the final structure will look like in the end and how it is suppose to resist the brutal forces. But how do you connect the start point and the end point? You just don't tie a rope to the space shuttle, you have to have some kind of structure.

Can anyone with clear ideas on the subject enlighten me on this one?

Re:How is this build?

[emorphien]

Theoretically it could be weighted and lowered in to earth's atmosphere by a satellite. Lowering it slowly would avoid the atmospheric resistance and thus not burn it up (similar to how SpaceShipOne survived the return portion of its flight).

In fact, in my mind reeling it out like a rope ladder from a high window is the smartest and easiest thing to do, the only catch would be watching the weather. But they plan to build this in a weather-friendly area anyway, so while it seems bizarre I suspect it's totally feasible.

Re:How is this build?

[RatBastard]

You start with the anchor satalite in geosync orbit and you drop the ribbon back down to earth with a weight on it to get it down to the ground. Then you connect it to teh ground anchor and move the anchor satalite to it's propper orbit. All done.

It's like a gigantic spider web.

Re:How is this build?

[Anonymous Coward]

> I really don't understand how this can be built!

We transport the whole cable to geo-synchronous orbit. Then we lower one end back to the earth while simultaneously feeding the other end into
deeper space as a counter weight.

As it is lowered, gravity will pull it down to earth, while centrifical force pulls the other end into space.

So there is no need to "attach the two ends" since you build out from the middle.

Or not...

[Dinosaur Neil]

...nothing new has to be discovered, nothing new has to be invented from scratch...

Uhhm, even in his book, Edwards admits that the carbon nanotubes needed to make this work just aren't there yet; while we can manufacture nanotubes now, we can't make them as strong (by a factor of around 100) or nearly as long (by a factor of 10,000 or more) as needed. While it may well be that, as soon as someone really puts some effort/research bucks into making stronger/longer nanotubes, they will happen, but it seems like 15 years might still be optimistic.

OTOH, this would be way cool, and maybe in my lifetime to boot...

Re:Or not...

[Inominate]

His statement is still correct.
We have the nanotubes, we can already make the composite materials needed.

We don't need to discover a new material, or create it from scratch. What we need to do is refine a material we already have in order to reach the required strength. The general consensus is that this can be done, it will just take some more work.

Maybe they should also...

[Rinikusu]

Build a roller coaster from space, to the earth... Slow ride up.. then massive whoosh on the way down with plenty of loops and turns and upside-down goodness! Imagine the tourism dollars that could go fund the lowly freight elevator next to it! And we could call it.. The.. Great Space Coaster! And hire a GNU named Gary! Or Richard...

But I digress...

Re:Maybe they should also...

[ari_j]

But I digress...

Dude...you did a hell of a lot more than just digress, there!

Re:How Far?

[Anonymous Coward]

except i thought geosync orbit was required? for the top of the elevator to remain directly above the ground spot it must be in geosynchronous orbit. Doing otherwise would create stress on the cable that could compromise it's integrity.

Of course, if we had enough of the cable and continually fed the line from the ground station, we could cause the cable to wrap itself around the earth's surface similar to a string on a yo-yo. :-)

Good idea but...

[Anonymous Coward]

How do we keep planes from flying into it? And I don't just mean accidentally.

Re:Good idea but...

[RatBastard]

How do we keep planes from flying into it? And I don't just mean accidentally.

The same way they keep planes from hitting the Shuttle. The airspace around it is closed tighter than a hummingbird's cloaca. Any unauthorized planes in that airspace woiuld be shot down long before they could get anywhere near it.

I'm Confused

[Rura Penthe]

I'm confused. All the technology is there? What about the technology to build carbon nanotubes of sufficient length to actually make the thing? That seems like a rather obviously lacking area which is preventing the construction of an elevator. Perhaps there's been some kind of advance of which I was not aware?

Re: no god this can't be appening!!!

[Kwantus]

45 min? Try a week. (Photocell-powered? try a month.)

Late Again Rory

[stratjakt]

What's the story?

Re:How Far?

[Anonymous Coward]

The center of mass would have to be at the point where you would be in geosynchronos orbit, not the farthest point.

3001 The Final Odyssey

[Anonymous Coward]

Arthur C. Clarke talked about a space elevator in 3001: The Final Odyssey (1997), and mentions that 1996 Nobel Prize in Quemistry, Dr. Smalley claimed that those buckytubes could be used to build such elevator.

Re:3001 The Final Odyssey

[justrob]

He wrote about it long before then in a book called The Fountains of Paradise.

It's all in the marketing.

[HarbV7.0]

I think Donald Trump should get involved and build one of his towers around it. Hell they could even develop a reality TV show around it, thus generating more revenue! All I can say is if that happens they better also work on those bags the pizza delivery guys use. Even though I may live on the 942nd floor I still want my pizza in less than 30 minutes and it better be hot!

Re:How Far?

[Anonymous Coward]

NASA says geosynchronous orbit is 36000 km = 22000 miles. I think the 62000 miles part must be so the centrifugal force keeps the cable taut. You could build a solid tower up to 62 miles, but a cable-elevator just wouldn't work at that distance.

in 15 years...

[Joe the Lesser]

I predict the space cable will be ready in 15 years.

Not for passengers

[AgentOJ]

I've read quite a few posts about "riding the space elevator." I'm under the impression (and yes, I RTFA) that the space elevator would be solely used to send cargo up to space. Astronauts would still get up to the ISS by conventional means, and then the space elevator would just be a cheap[er] way to get supplies up to them without worrying about sending up rockets. Unless I missed something, humans wouldn't be travelling on this space elevator at all.

Re:Not for passengers

[WillWare]

Cargo might be a good use of the thing. When I read about the thing a couple years ago, I got all excited and got a copy of Edwards' book. There are two big problems. One is that LEO is full of space junk flying around at 8 km/sec. Edwards' idea for that is to put the bottom of the elevator on a boat that tugs the elevator around horizontally to avoid the flying junk, and I see no reason why that wouldn't work, assuming you can track the junk well enough, and make the cable fault-tolerant/redundant. The other is that whatever or whoever rides the space elevator spends a week in the Van Allen belts, which are full of nasty radiation. That's probably fine for some materials (air, water) but we don't want that for people.

Re:Not for passengers

[qbwiz]

You think think that we would send up people on the more dangerous and more expensive rockets, and then send their cargo on the safer and cheaper elevator? Not to mention the fact that the ISS is well below (and travelling much faster than) geostationary orbit, so the supplies would still need rockets (with a lot of power) to get there.

Re:Not for passengers

[NoMoreNicksLeft]

Why not? This thing could be built out so huge, so thick, than any reasonable amount of cargo could be put on it (on up to the 10s of tons). Why not a a passenger car not unlike on trains? Even allowing a hefty fraction of mass for radiation shielding, it could be quite fun. Can't exactly call it slow, 1-2 days for a distance far exceeding the circumference of our planet. The space station at the end of it could become incredibly huge, with surface to orbit rates so low... am I wrong, or is there no problem with the station expanding laterally at geosync?

Re:Not for passengers

[Anonymous Coward]

So your space station is makeing rather fast circles (ellipses to be exact) at 300km height and your elevator drops it of at 60000 miles. Stopping the elevator at 300km and letting the ISS pick up the cargo is impossible, unless the astronauts got a mighty set of reflexes as they pass the elevator at around 20000 km/h. If you let it go all the way to 60000 miles you need rockets to slow the cargo down and bring it in a lower orbit, it would probably be cheaper then launching it from earth, but would it be more efficient?

Next problem that might arise is the need to move the cable not only for satellites (a few hundred in operation) but also for the thousands of pieces of spacejunk larger then 1 cm. An encounter with such a piece would probablyy make the cable make a nasty "snap" sound, which noone could ever hear cause it's space.

Thirdly, 60000 miles? Geosynchronous orbit is at 42000km from the centre of earth, how the hell are they going to keep the "weight" where it's supposed to be? Rockets? Unless they manage to keep the centre of mass at 42000 km I don't think it's possible, and you'll end up with 60000 miles of expensive ribbon wrapped around earth (2.5 rounds) and a small crater where the "weight" met earth.

Re:Not for passengers

[ThrasherTT]

A couple of rebuttals, mainly from the recent issue of Discover magazine:

So your space station is makeing rather fast circles (ellipses to be exact) at 300km height and your elevator drops it of at 60000 miles. Stopping the elevator at 300km and letting the ISS pick up the cargo is impossible, unless the astronauts got a mighty set of reflexes as they pass the elevator at around 20000 km/h. If you let it go all the way to 60000 miles you need rockets to slow the cargo down and bring it in a lower orbit, it would probably be cheaper then launching it from earth, but would it be more efficient?

I think the idea for this is using the elevators to lift the mass up to an appropriate altitude and letting it go. Part of the mass is a booster rocket to get the mass into the appropriate orbit. It'd take a whole hell of a lot less rocket fuel to do this than to launch it directly from Earth's surface. Taking the mass to an altitude above geosynch and letting it go would give it a huge boost for getting out of Earth's gravity well. As far as efficiency, they are planning on driving these things with lasers powered by solar cells. I forget the exact details, but they imply that the propulsion systems are one of the easier components to develop for the project.

Next problem that might arise is the need to move the cable not only for satellites (a few hundred in operation) but also for the thousands of pieces of spacejunk larger then 1 cm. An encounter with such a piece would probablyy make the cable make a nasty "snap" sound, which noone could ever hear cause it's space.

IIRC, the main rebuttal for this is that the cable will be much wider than the minimum required for the target maximum liftable mass, and that there will be "repair lifters" that go up on occasion to patch holes in the ribbon cable. For the larger, trackable space junk masses, the cable will be tied down to a mobile oil rig platform to allow for evasive maneuvers.

Thirdly, 60000 miles? Geosynchronous orbit is at 42000km from the centre of earth, how the hell are they going to keep the "weight" where it's supposed to be? Rockets? Unless they manage to keep the centre of mass at 42000 km I don't think it's possible, and you'll end up with 60000 miles of expensive ribbon wrapped around earth (2.5 rounds) and a small crater where the "weight" met earth.

Above geosynch orbit altitude, masses "moving" (quoted because it depends on your reference frame) at the speed at which the weighted end would be moving tend to want to leave orbit. Put simply, things trying to maintain synchronous orbit (staying over one spot) below geosynch altitude want to fall (not moving fast enough), things at geosynch altitude stay where they are (speed is just right), and things above goesynch altitude want to leave orbit (moving too fast). For example, the moon's orbital speed is 1.03km/s (about 2200 mph, or about Mach 3), performing one revolution every ~28 days. The speed of something maintaining a geosynch orbit at 60k miles would be insanely fast, revolving once a day (at that altitude, it would be moving at ~7.5km/s). That would put a lot of stress (not sure how to calculate that) on the ribbon, which is part of the reason it needs to be so strong. The centripetal force would keep the cable taut. The weighted end would be quite massive, enough that the relatively small mass of the lifter and its cargo wouldn't cause enough of a change in mass to the elevator system as a whole.

Also, if the cable were to be in danger of getting dragged down, they'd probably just let it go, and the weighted end would rip the ribbon out into orbit and away. I don't think they are too worried about it getting dragged down, based on the designs I've read about.

The article in the recent Discover goes into more depth than the article attached to this thread... it even goes so far as to claim that many of the scientists that attend these conferences end up signing on to help the Space Elevator along towards being realized.

Re:Not for passengers

[Anonymous Coward]

Nahh. We don't need big rockets with lots of power anymore to get into orbit. Just an airplane to get us up high, and a small craft with a couple of tiny rocket engines of its own to take that last little step into orbit.

Re:Not for passengers

[tgibbs]

IIRC, the main rebuttal for this is that the cable will be much wider than the minimum required for the target maximum liftable mass, and that there will be "repair lifters" that go up on occasion to patch holes in the ribbon cable. For the larger, trackable space junk masses, the cable will be tied down to a mobile oil rig platform to allow for evasive maneuvers.


Also, it is more a ribbon than a cable, oriented edgewise in the orbital plane to present the minimum cross-section area to particles orbiting in that plane. It would also be somewhat curved, so that a single unfortunately oriented particle cut not cut it all the way across. So it would need to be overbuilt to withstand punctures, and would have to be maintained to patch them.

Re:Not for passengers

[tgibbs]

Thirdly, 60000 miles? Geosynchronous orbit is at 42000km from the centre of earth, how the hell are they going to keep the "weight" where it's supposed to be? Rockets? Unless they manage to keep the centre of mass at 42000 km

Which is exactly the plan. A counterweight at the far end can be adjusted to position the center of mass exactly in geosynchronous orbit.

Re:Not for passengers

[RoboRay]

Who cares if a space elevator doesn't help much getting stuff into Low Earth Orbit. If we've got a space elevator, LEO is dead. Bypassed like the Azores.

Re:Not for passengers

[StarsAreAlsoFire]

Your response is well written -- much more so than my semi-drunk, friday night response would be.

I just wanted to add that any orbit BELOW geo-sync, would be fairly easy to attain. At least, much more easily than it currently can be. Here's why:

In order to know your orbit, you need to know a few things. If you know your velcity vector and your position (thats a lot of numbers, btw), you know your orbit. There are dozens of relationships that can be used -- velocity vector, alt-azimuth + vel. vec, etc, etc etc. More along our interests though: if you know your orbital inclination (we do, it is zero) and you know your velocity (we do, it is always tangential to the earth, and it is always (um, that nifty equation that relates pi, R and omega, where pi is, errr, pi, omega is 1/(86400) hz, and R is your current altitude....). Given the 'multi day' trip speed, I have neglected the 'upward' portion of the velocity. If I really cared I'd model it in STK -- so if you were smart enough to catch that, kudos, and leave me be.

ANNNNYYYY WAY. What I am trying to say is that we just 'let go' a little bit higher than our desired orbit, then make a *small* orbital correction. Assuming that we WANT an equatorial orbit. Now, if we don't, the course correction is NOT minor! But it is still a small fraction of what we would have paid to launch from the surface of the planet, unless we want a polar orbit at some very low altitude...... now just WHO might want that?

And if you are wondering, I have a degree in astronautical engineering. Does that mean that the above is right? Not at all! In fact, the bottle of wine I just helped finish says there is a good chance I am full of shit! No math was even attempted in this analysis....

Re:Not for passengers

[Qutec]

Are you going to leave any showstoppers for them to figure out?

They just got 2.5M and you squashed the idea in a few paragraphs on /.

I would go looking for my consultant fee.

Re:Not for passengers

[dekeji]

Next problem that might arise is the need to move the cable not only for satellites (a few hundred in operation) but also for the thousands of pieces of spacejunk larger then 1 cm. An encounter with such a piece would probablyy make the cable make a nasty "snap" sound, which noone could ever hear cause it's space.

I'm not particularly enamored with the idea of a space elevator, but this particular issue does not seem to be a problem.

It's not one cable or multiple cables, it's multiple cables with cross-connections. A lot of stuff can hit them before the entire structure fails.

Re:Not for passengers

[Anonymous Coward]

You think think that we would send up people on the more dangerous and more expensive rockets, and then send their cargo on the safer and cheaper elevator?

Yes. Just like people travel overseas on more dangerous and more expensive jet planes and then send cargo on safer and cheaper container ships.

Re:Not for passengers

[qbwiz]

Not quite. That didn't get to orbit, only to suborbital velocities. While it is a big achievement, they have to go much, much faster to get to orbit.

Re:Not for passengers

[ThrasherTT]

And if you are wondering, I have a degree in astronautical engineering. Does that mean that the above is right? Not at all! In fact, the bottle of wine I just helped finish says there is a good chance I am full of shit! No math was even attempted in this analysis....

Excellent. I don't have a degree in astronautics, but I did work for a competitor of AGI, building a "simplified" STK-style app (FreeFlyer, built by AI Solutions). I tried to keep my post simple for two reasons:

1) I wasn't sure how much I mis-remembered
2) I wanted to keep it non-technical enough for the AC that I was responding to, since s/he seemed to be missing some pretty important points of orbital mechanics

Re:Not for passengers

[modavis]

Based on a presentation at the SE conference this week, you're right about the Van Allen belts. Most likely humans will still use rockets until the 200-ton and bigger elevators are running (could be just a couple of years after the first one, depending on how much capacity you sell vs. lifting material to build bigger). At that point, instead of a sleek Bullet Train to Heaven, you may see a big "igloo" of ice maybe 2' thick, which should be adequate shielding. Lots of water will be handy in orbit in any case. Beyond drinking and shielding, it makes a good dump if you don't want HUGE radiators...

tower of babel?

[Anonymous Coward]

This one is going to make the tower of babel look like a sand castle. What's god going to do about it this time? Knock it down and scatter us across the world and force us speak different languages? Ha!

Two birds with one stone

[siliconjunkie]

You could have "love in an elevator" *AND* join the "mile high club" at the same time!

But wait..

[kinobsd]

This already does that, PLUS it goes frontways, backways upways, downways and any way at all!

WAAYYYY TOO OPTIMISTIC

[mcrbids]

When you are dealing with something as major as a space elevator, you don't just rush out as soon as you could possibly build it, and then build it!

This scientist is clearly ignoring the political aspects of building something like this and focusing just on the technology.

Cell phones have been essentially possible since the 1960's. It took some 30 years to work out the kinks, and to get people's heads around the idea, develop the necessary infrastructure, etc.

You have to test it! Get people to see it in the real world so that they see and trust this new technology before we go do something outlandish like build a space elevator!

Do something a little more down to earth, to give us the chance to find the inevitable flaws.

Suspension bridges - I can't think of a better real-world test scenario! Would the cable even be big enough to see from the shore?

One going across the straights of Gibralter would be nice...

Scary

[Anonymous Coward]

What if some huge ass alien comes around in 20 years, sees our cable and just slings us into space?

Scary. :o(

Re:Scary

[Garion Maki]

giant space jojo with earth in the middle :D

Refuting some silly comments

[edwinolson]

Some folks think it's a typo, that it's supposed to be 65 miles, not 65K miles. No, 65K miles is more like it. You really want your elevator's center of mass to be in geosynchronous orbit... Space elevators to LEO tend to, uh, get wound around the earth right fast.

And if the ribbon breaks, things generally aren't so bad. The portion of the elevator (including the counter weight) that's further from the earth will tend to move away from the earth. (If you spin in a circle with a rock in your hand, then let go of the rock, the rock goes away from you, not crashing in towards your head.) The nearer part will tend to fall, but it will tend to fall slowly and is relatively unlikely to cause damage. (At least, according to High lift systems, who came and gave a talk last year.) The elevator, since it's so huge, tends to not be terribly heavy. The system proposed by high lift systems

I believe Brad Edwards was involved in High Lift Systems, so I imagine the basic idea is the same.

If geo is ~20K miles, why does the elevator need to be so long? Does this mean that they're now thinking about a lighter counter weight? They used to talk about capturing an asteroid.

Re:Refuting some silly comments

[Anonymous Coward]

"(If you spin in a circle with a rock in your hand, then let go of the rock, the rock goes away from you, not crashing in towards your head.)"

I was under the impression a human head would not have sufficient gravity to pull a rock into it. The earth is somewhat larger and has somewhat more gravity about it.

Re:Refuting some silly comments

[Ion Berkley]

OK I haven't thought this out too much so don't flame me too much if I missed something obvious but:
Geostionary orbit is the distance from the earth that an object with angular velocity that keeps in stationary orbit over the same point on the earth is at equilibrium from centrepetal aceleration and gravational attraction.
Assuming that statement is correct then to support the weight of the 'cable' and payload which are deeper into the gravity well of earth then the endpoint needs to be much farther out than a normal geostationary orbit so that the force generated by centrepetal acceleration minus gravitational attraction of the whole system still has a resulting force vector that tensions the cable..... ....does that make sense to anyone!?!?!

Re:Refuting some silly comments

[Jeremi]

Yes, that is correct -- the cable needs to extend past the level of geostationary orbit. It can either extend a long way past that level, or it can extend a shorter distance and have a counterweight tied to the end. Geostationary orbit is still a useful place on the cable to put a space station though.

Re:Refuting some silly comments

[ThrasherTT]

If geo is ~20K miles, why does the elevator need to be so long? Does this mean that they're now thinking about a lighter counter weight? They used to talk about capturing an asteroid.

Last I read, they are planning on using lighter counterweights: I mentioned it here

Re:Refuting some silly comments

[Anonymous Coward]

why does the elevator need to be so long? They used to talk about capturing an asteroid.

As long as the mass beyond geosync is correct, the shape doesn't matter.

So, it probably occurred to someone that a long, thin, cable would have an end that moves at higher speed than an asteroid at geosync. A long cable would be better as a launch system. An asteroid might be useful for raw materials or just mass if you want to turn it into a space station. But it's also hard to capture that asteroid, so you might not want to make your design dependent upon having one handy.

Re:Refuting some silly comments

[Anonymous Coward]

The elevator must be so long because it's not the center of mass that must be in geosynchronous orbit, but rather the center of gravity. Portions of the elevator close to the earth will experience much greater gravitional forces, so additional material beyond geosynchronous orbit is needed to compensate.

A basic formula to solve for the required length and illustrate this balance is:

integral(density(x)*[G*Me/x^2 - (2*pi/T)^2*x],dx) from re to (re + length) = 0

where:
density(x) = linear density (kg / m) of cable at altitude of x meters
G = gravitational constant (6.673e-11)
Me = mass of earth (5.976e24 kg)
re = radius of earth (6378137 m)
T = rotational period (~86150 s)

this cable can support 13 tones

[eadint]

OK multiply that by 100 and you might be able to support the cable alone. multiply that by 500 and you might be able to send a can of pepsi up to space.

Re:this cable can support 13 tones

[PoiuyTerry]

How many cans of pepsi do you know of that weight 13 tonnes?

Re:this cable can support 13 tones

[eadint]

none
But the infrastructure and equipment needed to move one can that high and far would way more than 13 tonnes

Technology is advancing at an incedible speed.

[LuckyStarr]

Processes to make fibres of nanotubes have allready been developed:

http://www.nature.com/nsu/040308/040308-10.html
http://www.technologyreview.com/articles/rnb_0412 0 4.asp

Re:Technology is advancing at an incedible speed.

[Anonymous Coward]

I guess you never got to the part where it says

So far, the fibres aren't outstandingly strong -- they're no better than typical textile fibres. But Windle thinks that there's still plenty of scope for improving the process to make stronger fibres, for example by finding ways to make the nanotubes line up better....

But it's not clear whether the method will ever produce fibres as strong as the individual nanotubes that comprise them: to do that, each nanotube would need to be as long as the entire fibre.

Re:#1 thing not to say about a space elevator cabl

[ari_j]

#2: In emergency, USE STAIRS

spoiler

[SQLz]

They should put a spoiler on it at the top. Carbon fiber, and some rimmmzzzzz zz zz.

Re:How Far?

[np_bernstein]

I'm guessing he actually did mean 62 miles. The point is to reduce the cost of getting things out of orbit. Once there, if you want to get up further, you launch a shuttle from the top of the elevator. 'Sides, I would think they'd want to keep the costs down as much as they can. There is a /slight/ difference in costs between 62 Miles, and 62,000 miles.

Sounds like a lot of big talk...

[Anonymous Coward]

Seriously, I don't want to undermine the scientist who obviously (from a Google search) is very experienced/talented, but this report sure makes it sound like a lot of baloney.

All he seems to be saying is, in his own words: "It's not new physics -- nothing new has to be discovered, nothing new has to be invented from scratch".

The "physics" part IMHO is usually only half (or less) the battle won - just because the "physics" is in place doesn't mean the problem is solved. The major obstacles are almost *always* something which has nothing to do with the original problem.

I hereby predict that we can go visit the Andromeda galaxy. "It's not new physics"...but Oh - you have to figure out a reasonable way for the crew to stay alive during the journey - that's a biological problem.

I also predict that flying cars will be the way to travel in the next 5 years - but yeah, we've to figure out a way to make it safer, it's safe from the "physics" point of view, but the engines would need to be so huge and noisy that nobody in their right mind would buy it. And yes, there's a little work to be done in order to make it safe too - but that's not really our problem.

Seriously, I never doubted that we could come up with a material light enough and as strong as steel in order to make the Space Elevator a practical possibility. But the surrounding problems (I could name a few, but I'm too drunk right now) are the ones that need to be solved before making lofty predictions.

And before I forget *hic*...Hiya to all the other Slashdotters spending their Friday evenings at home.

lazy bums

[Anonymous Coward]

Whats wrong with stairs?

Getting a counterweight?

[Faies]

Nothing in the article mentions the feasability of getting a decently sized counterweight at the top of the elevator. All plans I've heard of require at least some sort of asteroid...and if you're talking politics, people are going to be afraid of dragging a rock into Earth orbit that could smash into the planet a.la if something went awry.

Re:Getting a counterweight?

[Fzz]

Could you use the elevator itself to lift the counterweight? You start off with a small counterweight and an even smaller elevator car, and make multiple trips, each one increasing the mass of the counterweight. As the counterweight increases you can bring up more additional counterweight mass each time, until you've got enough to allow you to substitute a larger elevator car.

Re:Getting a counterweight?

[molo]

The counterweight isn't for the car, its for the elevator itself. The *center of gravity* of the elevator must be at geosynchronous. If the elevator only consisted of the cabling, it would have to be 2x longer than the distance to geosynchonous orbit. Capturing an asteroid to use as a counterweight would mean that the cable would only have to go a couple hundred miles past geosynchonous - depending on the mass of the cable and the asteroid. (remember geosynchronous is 35790 km (22240 miles) above sea level)

-molo

Re:Getting a counterweight?

[sessamoid]

Nothing in the article mentions the feasability of getting a decently sized counterweight at the top of the elevator. All plans I've heard of require at least some sort of asteroid...and if you're talking politics, people are going to be afraid of dragging a rock into Earth orbit that could smash into the planet a.la if something went awry.

We've got so much damned space junk at various orbits (old satellites, star wars-type platforms, pieces of ISS, etc.) that we could just tow a bunch of that crap together and build an anchor out of that, couldn't we?

Re:Getting a counterweight?

[kfg]

Nothing in the article mentions the feasability of getting a decently sized counterweight at the top of the elevator.

Reports are that engineers have been seen stalking Rosie O'Donnel and Anna Nicole Smith.

KFG

Re:Getting a counterweight?

[NoMoreNicksLeft]

Why not lift material to build the couterweight out as a traditional station?

Re:Getting a counterweight?

[mangu]

But the article mentions a 62000km height. That's about 50% longer than would be needed without the counterweight.

Re:Getting a counterweight?

[molo]

Notice the length of the cable in the article:

"62,000 miles into space"

Notice also that the distance to geosynchonous orbit from sea level is 22240 miles. This means that the cable will go well beyond geosynchonous and will essentially act as its own counterweight, with the center of gravity at the geosynchonous orbit. No asteroid required.. but the cable has to be much much stronger since it would be three times longer and must support its own weight.

So, the statement of "nothing new has to be discovered" I think is incorrect. There is no carbon nanotube that can withstand that tensile force yet. There is also no way of manufacturing carbon nanotubes of this scale.. let along lifting it to orbit intact (or reassembling the different spools in orbit). 15 years is wishful thinking.

-molo

Re:Getting a counterweight?

[Anonymous Coward]

Quick! Do it before Bruce Willis gets much older!

Re:Getting a counterweight?

[Ralph Wiggam]

"There is also no way of manufacturing carbon nanotubes of this scale"

These are the kind of problems that a bunch of money can solve. Instead of spending billions on a missile defense system that has never worked, maybe we should do something usefull.

-B

Re:Getting a counterweight?

[DanielJosphXhan]

Well heck, if we're going to tether it to an asteroid, why don't we use a bunch of these things and tether it to the moon?

Not to mention you'd get rid of those pesky tides.

Re:Getting a counterweight?

[chgros]

but the cable has to be much much stronger since it would be three times longer and must support its own weight.
The weight would be the exact same as that of a counterweight (to keep the center of gravity at the same place), so you are wrong here.

Re:Getting a counterweight?

[molo]

Yes, i think you are right. Thanks for the correction.

-molo

Re:Getting a counterweight?

[spitzak]

The proposals all assumme a length of cable beyond geosynchronous orbit, and possibly left over machinery from the cable building, would serve as the counterweight.

A longer cable is actually useful, as it can be used to throw things out of Earth's orbit, such as to get to other planets.

Re:Getting a counterweight?

[ThrasherTT]

As far as I understand it (from the recent Discover article), once the ribbon is initially deployed (starts out small), they send up small lifters that build onto the main ribbon, increasing its width. These initial lifters would park at the end of the cable forever, increasing the size of the counterweight. They claim that the initial ribbon would take about 2 years to build to full width with this method. Additional ribbons could be constructed in 7 months each, for MUCH less cost... after all, they can use the first elevator to start the construction, instead of sending the initial materials up on big tanks of burning rocket fuel.

Re:Getting a counterweight?

[jsebrech]

These are the kind of problems that a bunch of money can solve. Instead of spending billions on a missile defense system that has never worked, maybe we should do something usefull.

In all fairness, the space elevator has never worked either.

I don't know if the star wars program is any more unrealistic than the space elevator. Hitting a moving target that fast is hard, but not impossible. On the other hand, if you're comparing launching a system that upsets the worldwide nuclear balance and doesn't have any practical uses other than global thermonuclear warfare (better known as the apocalypse), and launching a system that unlocks space for all of humanity, it seems to me the choice should be obvious.

Go star wars! ;)

Re:Getting a counterweight?

[solarlux]

> On the other hand, if you're comparing launching a system that upsets the worldwide nuclear balance and doesn't have any practical uses other than global thermonuclear warfare

How short-sighted. Does stopping an ICBM launched by a rogue nation or terrorist group toward Manhattan constitute a practical use? And by your logic, the USSR's construction of ABMs around Moscow should've resulted in world war 3.

International development of an ability to safely diffuse ballistic high-speed high-yield explosive devices is a very positive progression in light of desiring world peace. I hope that within 15 yrs, all countries are protected by missile defense systems. Perhaps humanity may survive through the century yet.

You forbid it.

[LuckyStarr]

The proposed location is also very remote (somewhere in the pacific ocean) and can easy be made off limits for flight-lines.

I also can not see what a terrorist could gain from destroying a fanal of humanitys transition to become an interplanetary race.

Re:You forbid it.

[DarkMantle]

It would be a symbol of freedom... that's why we had 9/11

Because of the metric system...

[Anonymous Coward]

Well, first of all, he'll have to adopt metric units or they'll never make it off the ground (or crash back there harder than planned, and that's not just onto uninhabited Mars this time).

Here's what happens all the time when you try and compute in Imperial measures (thought the U.S. had quit Britain a while back in time, so why keep using these units anyway?):

62,000 miles... actually that's some kind of orbit too, but what are you trying to catch that far out there? Add just a few inches (SCNR) and this elevator takes you to the lunar surface as a matter of fact....

Elevator? Hmmph

[bravehamster]

I'll just wait for the Space Escalator, thank you very much.

Just you parents make sure your kids aren't wearing loose jeans on the escalator!

A little more humility is in order

[Beryllium Sphere(tm)]

Material science is still partly empirical and it takes time to learn all about a new material.

After thousands of years of using iron and steel we still had bridges falling down in the 19th century.

Composites have been around for a generation and Boeing is only now willing to put them in the majority of a jetliner's structure. As recently as a few years ago aircraft composites were coming up with unexpected problems like delamination.

It could take fifteen years just to write the handbooks about using nanotube fibers in ionized oxygen and in the van Allen belts.

Re:A little more humility is in order

[conan776]

>Composites have been around for a generation

Of course, studies showed people freaked out if there weren't any bolts in the wings. I think they glued fake ones on for a while....

Re:A little more humility is in order

[Anonymous Coward]

It could take fifteen years just to write the handbooks about using nanotube fibers in ionized oxygen and in the van Allen belts.

You're not going to learn what to put into the handbooks unless you try building the thing. People spent thousands of years building bridges, and a couple of hundred building them out of iron and steel, and having them fall down, before they wrote those handbooks. If everyone waited until someone else wrote the book, we'd still have nothing but ferries.

Re:A little more humility is in order

[jackbird]

After thousands of years of using iron and steel we still had bridges falling down in the 19th century.

When, exactly, did the production of steel on a scale that one could build a bridge out of the stuff begin? Iron, too, for that matter? Certainly not thousands of years ago.

Furthermore, it was mostly the math that needed improvement, not the materials.

Re:A little more humility is in order

[betelgeuse-4]

During the 1770s

Re:A little more humility is in order

[Anonymous Coward]

Furthermore, it was mostly the math that needed improvement, not the materials.

Actually it was both. Steel today is something completely different from steel a hundred years ago. Our understanding of how steel works has grown tremendously.

There will never be a space elevator

[second class skygod]

Before we ever overcome the technical, political, and financial problems imposed by a space elevator, we will find better ways to get into space. You heard it here first.

-- scsg

Space elevator + terrorism = disaster

[Hibernator]

Doesn't anyone read Science Fiction anymore? Kim Stanely Robinson gave us a nice vision of what can happen if you knock down a space elevator in his Red Mars, Green Mars, Blue Mars trilogy.

Where would it go?

[Hackie_Chan]

From: Some building on Earth.
To: Uhm, space?

I mean, seriously. Where would it end at? Otherwise it'll just be a 10 billion dollar murder machine launching people in to space so they die.

Re:Where would it go?

[NoMoreNicksLeft]

It would end 60,000 miles up. You wouldn't have to ride to the top, the important orbital destination will be halfway up, and likely a big space station. You could ride to the top, build a spaceship to go to mars docked at the end, and then just unclamp it when ready, and let the earth fling it there.

Or you could stay awhile, moon australia, and then take a car downward.

You could make a amateur satellite out of tin foil and fig newtons, and push it out an airlock in the middle. Wow, Cletis is now capable of putting objects into geosync orbit.

We could build several elevators, and then "bridge" them together in the middle, and put an incredible amount of real estate into action.

In short, it would never end. It would be the first step in a journey to just about anywhere. Though for now, most people think locally, and its a road to high orbit.

Re:Where would it go?

[Anonymous Coward]

"What are you here for? We are all here... we are all here to go. Earth is going to be a space station, and we are here to go! Into space! That's what were here for..."

-- William S. Burroughs, Dead City Radio

foolish idea

[Anonymous Coward]

a space elevator is not even possible, consider violent weather conditions such as thunderstorms, Tornados, hurricanes, ice buildup etc...etc...

it will never be sucessfull, NASA just considering this idea just shows how NASA has run out of good thinkers in their R&D dept...

maybe it is time for private industry to take over space exploration...

But I still am waiting for.....

[3seas]

... my flying car..... they promised me a flying car....

I've seen the Institute.

[NarrMaster]

I live very close to Fairmont, and have passed the Institute many times during its construction. Nothing ever really happens in WV, so its refreshing that a good idea for space exploration is coming out of this so-called "hick, backwards" state. Anyway, back to the point. I am applying for a job there after my masters is completed here at WVU, or where ever I end up. Not sure if there's a need for Math degrees, but hey, I can try, right?

Here is a link to photos of the construction.
ISR

What about coriolis force?

[mpn14tech]

How is coriolis force going to be handled.

Since velocity=(radius)(angular speed) then there has to be a tangential acceleration as the elevator starts going up.

Obviously tension on the cable can be used if you do not go up too fast or send up too much mass at one time.

Of course the talk as always about using this to go up, but would it be possible to use this as a really big sling shot to launch space craft around the solar system.

Re:What about coriolis force?

[Anonymous Coward]

I would think you would build it anchored at the equator as much as possible.

$10 billion or 10 trillion?

[harvey the nerd]

This is a vital technology but...3 ft Pipelines (say 36" X65), mere steel steel shells say 1/3 to 1 inch thick, usually cost (usually way over) over $1 million / mile on terra firma. Not to mention how much super carbon fiber rod(nearly solid 3ft??), flying it up, joining in place. Try some multiple of $100 billion at least. $10b sounds like someone's "too cheap to meter" on nuclear power 50+ yrs ago. We got "nuked" financially.

Re:$10 billion or 10 trillion?

[TheMadReaper]

If you compare the mass per mile of the space elevator ribbon with the mass per mile of the pipeline, you will get a better idea of the difference. I estimate that the elevator ribbon will be about 25kg/mile. The pipeline certainly weighs many tons per mile, I'd say at least 10. So the material costs per mile are a lot less for the elevator than for the pipeline, even if the ribbon material costs an order of magnitude more than the steel for the pipeline.

Next, you clearly haven't looked at how they intend to build up the elevator. They will start by deploying a thin initial ribbon; this is the only part that has to be flown up with rockets. All the rest of the ribbon mass will be built up by sending spools of ribbon material up along the elevator on "climbers". They will build up the ribbon cross-section as they go. The labor costs will be minimal compared with pipeline laying. Also, there won't be any terrain difficulties to overcome, unlike pipeline construction. No mountains, marshes, etc...

Get a boy scout

[Fished]

To knot the nano-tubes together. Geesh!

While you're at it, you could rub his legs together to make a fire for the coming ice age caused by a 62,000 mile long cable giving earth a massive whiplash.

Boy Scouts are better than duct tape.

The first person to ride wins a prize

[Anonymous Coward]

A voucher for the soon-to-be-released Duke Nukem: Forever.

Re:How Far?

[Rei]

No, he didn't. If you release at 62 miles, your orbit intersects the Earth quite quickly. If you release later but before GEO, you can get highly elliptical orbits whose outermost radius is at the elevator; beyond GEO but not too far, you end up in an elliptical orbit whose closest point is at the elevator. Beyond a certain point after that, you get flung off out into interplanetary space, sapping your energy from Earth's rotation. :)

no new physics?

[Goldsmith]

The nanotube thread we can make now is not strong enough to work. What we need is a way to "weld" nanotubes together without introducing massive defects (that's key). There's a significant amount of physics to be done there.

On the other hand, we've been able to increase the size of the nanotubes we've been able to grow an order of magnitude every few years. We're up to centimeters now for one, single tube, and the process is likely scalable (as in, bigger furnace, longer tubes).

To get an idea of how hard this would be:

62000 miles is about 1*10^14 micrometers,

There are about 3.2*10^7 seconds in a year,

nanotubes grow at around 300 micrometers a second,

so it would take 10,000 years to grow that elevator out of continuous tubes (unless we're way, way off on the speed).

I'm not sure about 15 years, but I think we'll get it done sometime in the next 100 with some sort of welding technique, and in the long run, it's going to cost a lot more than anyone now thinks.

Re:no new physics?

[John Hasler]

There is no need for the fibers to be continuous.

Re:no new physics?

[Eivind]

But noone is suggesting we build an entire space-elevator of a single molecule 40000km long, that is, as you demonstrate, clearly unreasonable. (allthough your math is a bit questionable, because you jsut assume it'll not be possible to start by growing a few million relatively short nanotubes, then somehow get two and two of those to fuse into one longer one, and so on until you've got one long instead of many short fibres.

epoxying together the short fibres to make a ribbon or cable that has strength in the same ballpark as the individual fibers is indeed a challenge, but not nearly as big a challenge as you seem to think.

One thing you overlook is that if you double the average length of the fibers used, you halve the needed strength for the "glue" used. Se below ascii.

short fibers: xxxx xxxx xxxx xxxx xxxx xxxx xxxx x x xxxx xxxx xxxx xxxx xxxx xxxx xxxx xxx xxxx xxxx xxxx xxxx xxxx xxxx xx Long fibers: zzzzzzzzzzzzz zzzzzzzzzz zzzzzzzzzzzzz zzzzz zzzzzzzzzzzzz zzzzzzzzzzzzz zzzz zzzzzzzzzz zzzzzzzzzzz zzzzzzzzzzzzzzz Obviously, in the latter example, the glue a weaker glue will do, because the individual fibers have the same strength, but a larger surface for the glue to work on.

The illustrations exxagerate grossly offcourse, even todays "short" nantubes are thousands if not millions of times longer than they are thick.

I've seen claims that if we could make individual nanotubes in bulk, 3cm long each on the average, then even todays weaving and gluing techniques would suffice to give the finished cable 90% of the strength of the individual fibers with only 30% weigth-addition to that of pure fibers. If the math in that checks out I dunno, and I can't seem to find the reference, so it's even possible I misremember that.

Erm, uh, no.

[NarrMaster]

Refer back to the last time the space elevator was covered for refutation by others who state it much better than I can.

Slashdot.org

Re:Erm, uh, no.

[Canadian Idol]

I don't think the problem is (massive) destruction on Earth. The problem is a vulnerable base station that will allow you take out a multi-billion-dollar hi-tech project, a project that shows 'superiority' of science. It's an Osama-magnet!

Re:Erm, uh, no.

[NarrMaster]

If its out at sea, I think a few carriers can handle that. Provided he's not captured by then.....

Re:How Far?

[NoMoreNicksLeft]

If the end of the elevator is only at geosychronous, then it has thousands of tons of weight pulling it downward. But since anything *past* geosync actually flings the object away from the planet, you put just as much weight on the other side of geosync, performing a nifty balance. As for why its not 45k miles, I can't say. Seem to remember it tapering at the end quite a bit, for some engineering reason.

Best of all, go out to the end of it, let go.... you get a free trip out of orbit. Be sure to bring plenty of food and water.

Re:How Far?

[Anonymous Coward]

The La Grange points are somewhere in Texas.

The Lagrange points, at least the first two, are about 1.5E6 km from us. These are named after Joseph-Louis Lagrange. He is a pretty fameous mathematician, though by now I suppose the bordello in LaGrange is pretty fameous too.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Some terrorist kook would destroy it

[Anonymous Coward]

so what's the point

Re:How Far?

[maysonl]

The guy meant 62,000 miles, because to keep the thing in orbit (and it is in orbit), and attached reasonably permanently to the same region on earth, the center of gravity has to be in geosynchronous orbit, about 25,000 miles out. Thus the counterweight has to extend quite a ways beyond geosynchronous orbit.

elevators

[preposterity]

no wonder we have an obesity crisis on our hands. can't people just take the stairs?

This whole space elevator business is just nuts

[Anonymous Coward]

We only need to break out our UFOs out of area 51 and quit spending our time on pie in the sky ideas.

Re:This whole space elevator business is just nuts

[Anonymous Coward]

You know, what is sad is the fact that this poster might actually be serious!!

Re:How Far?

[mangu]

I think the 62000 miles part must be so the centrifugal force keeps the cable taut.

Nah, it's just another NASA rocket scientist [sic] trying to figure out that unit-conversion software thingie.

Bad name 'space elevator' try ' space cable'

[DRWHOISME]

Shouldn't be space elevator because that has wrong connotations.

Should be called Space Rope or Space Cable.

Space Elevator was a scifi term and meant building a very tall building or structure to be used as an elevator.

This is 'not' that.

Re:How Far?

[jefe7777]

and this wonderous carbon nanotube material?

i'm sure the military would interested in a few sheets of that stuff to drape over their tanks.

michael jackson might want some for his playland.

Re:How Far?

[Anonymous Coward]

62,000 miles is correct. The top of the elevator "shaft" has to be at geosynchronis orbit altitude, which is around 36,000km. You then need to add a counterweight to the other side of the elevator head of equal force (ie it needs to weight the correct amount at the right distance past the elevator head). This is where it gets to 62,000 miles or there abouts.

Elevator is an excellent name.

[LuckyStarr]

It means what it does. To elevate things very high. So...

Re:Elevator? Hmmph

[Anonymous Coward]

...that kid is BACK on the SPACE ESCALATOR!

Supply Elevator

[deathcloset]

The space elevator coupled with a nuclear rocket is really the way to get things going (in my blissfull imagination).

The moon base is looking better and better, closer to 'reality' everyday...or every year, I should perhaps say.

The nuclear rocket would be great for getting the inital big heavy stuff up into space; primary building materials, the initial spools and anchors, people..etc..

I would think the space elevator would be good (at first) to reserve for hefting non-living things like food, water, and my personal favorite - oxygen, up to the anchor station and transfering them to the moon-base's anchor.

From the earth's anchor-station you basically just give the big 'ol bag of air a nice gentle push (maybe use a 'simple' solar sail, and who cares if it takes a month to make the journey over to the moon anchor (I think it would probably take less); becuase you'll have already sent 1000 ('cheap') other bags of supplies already in transit; a nice, floating convoy of happy consumables/breathables migrating on over to the moon (and back for recycling). Nice perpetual supply chain.

Heck, you could just have a 'snorkle' tube, dipped into the atmosphere, drinking up oxygen and water to fill the supply balloons. Dedicated supply elevators. When they get to the moon, empty them out and send 'em back.

To get the people to the moon base we would use the more-funner nuclear rocket ship (at first).

Now what if the ribbon breaks? you just have to ask, don't you? of course you have to ask; if you didn't you'd be ignorant (which is supposed to be bliss, but were that true there would be more happy people).

Well, if the ribbon breaks, that sucks. Basically you just make sure you have contingency, two elevators/ribbons and a good insurance agent. That way you can keep the lifeline going while we change-out the nanotube-paper-towel-roll on the other elevator.

As for the 62,000 miles of ribbon falling to the earth - the worst place for a break would be right at the anchor. This would mean the entire ribbon would begin falling to earth. This problem could be handled via several means. one way we could do it would be to have some sort of explosive bolt system that would blow the cable into small segments that could burn up in the atmosphere...hopefully (maybe they would be light enough, with enough drag to simply flutter down (let's just not worry about the unfavorable aspects of nanotube particles in the atmosphere for now - we, uh, have a glue that keeps them from turning into horrible carbon dust..yeah).

the other, more conservative method would be to have a quick retract device at the ocean-based-mobile-ground-station (ocean, ground, mobile, station...some oxymorons there) This would spool down the elevator ribbon at a speed that would keep it from 'tipping'. resulting in a straight to the ocean floor descent (imagine a kite's-tail - only vertical).

Perhaps the ribbon could even have parachute points at intervals along it's ascent. Long and short of it - if I can start dreaming up ways to handle this I think a couple physicists could figure something up that would work.

TERRORISTS!!! WHAT ABOUT THEM!? Sure, they crashed a civilian plane into the pentagon. But they didn't crash it into an airforce base, now did they? Why? S.A.Ms.

It sounds wild, but to me the space elevator just seems so elegant; almost natural. I mean, carbon; come on. We all Love carbon right? -(my friend mike for some reason hates carbon, but he's a chemist and that's another story)

I always think of the analogy of space as a tall cliff. You need to get to the top. Do you..
A) catapult yourself up there, try to land on your feet without breaking things and then base-jump back down?

or

B) throw a grappling hook, climb up, and climb down?

can you think of a better non-explosive way to get to space?

Re:Supply Elevator

[LuckyStarr]

Nice post. Would be total crazy!

I want to remind you that once one elevator is ready a new one can be built for far less money then the first one. So we can have...say 2 of them for the price of the first one, because transportation is now cheaper as its our business now and not the rocket stinkers. Thank you, universe!

People are all confused about the space elevator.

[Baldrson]

The real question here isn't whether the technology exists to do a space elevator.

The real question is "Where will the next huge centralized government-funded project come from to scare private capital away from making access to space affordable for another 30 years?"

Re:How Far?

[l810c]

Yep 62000, it's all explained in their FAQ

62000mi == 100000km

[mangu]

looks like someone rounded an SI measurement

Its so very more than that.

[LuckyStarr]

Its a symbol for mankind to take pride in their achievement.
Its a symbol that the universe is out there for us to expand to, and we can!
Its a symbol of progress! Its something that can trigger something an any person on this planet.

Mankind can create something that is so big that interplanetary distances seem not so big anymore!

And to add: Not the symbol of freedom caused your 9/11. I sympathize with your condition though. Would be a shock to me too.

Re:How Far?

[Anonymous Coward]

" No, it *is* 62000 miles. The tether has to be that long to allow a suitable anchor to be attached at the other end "

Why not use a skyhook? :-)

Now.. where did I put that long stand for my left handed axe...

Willy Wonka

[Hybby]

This sounds like something taken directly out of Willy Wonka and the Chocolate factory.

Can it go side to side also?

I can see it now...

[DMadCat]

"Yeah," said Zaphod, stepping into it, "what else do you do besides talk?"

"I go up," said the elevator, "or down."

"Good," said Zaphod, "We're going up."

"Or down," the elevator reminded him.

"Yeah, OK, up please."

There was a moment of silence. "Down's very nice," suggested the elevator hopefully.

"Oh yeah?"

"Super."

"Good," said Zaphod, "Now will you take us up?"

"May I ask you," inquired the elevator in its sweetest, most reasonable voice, "if you've considered all the possibilities that down might offer you?"...

Damn futuristic elevators... 62,000 miles of that? No, thanks!

where does the kinetic energy come from?

[cdn-programmer]

The "real" issue is where the Kinetic Energy comes from. Space Ship 1 proves that a small relatively inexpensive craft can attain the elevation needed to reach space. What Space ship 1 did not have is enough energy to reach orbital speeds. The additional energy is over 30 times more than required to reach the elevation.

Now a space elevator has the exact same problem. Somehow this energy has to be fed into the system.

Now - suppose we launch into space a tether and rotate this teather in the opposite direction to orbit so that the relative velocity of the tether when it picks up a spaceship is low. This tether will need to impart kinetic energy to the craft and perhaps this can be done through some sort of electrical propulsion system. If so, then free sunlight from space can be collected to provide the electricty.

So just maybe there are hybred systems that will work.

--------------

One way a tether system could be used is to use a baloon to raise the ship to a high elevation and then drop a tether down. Of course baloons can be attached to the space elevator cable itself... but why bother? You can simply lift the elevator car.

Now - this is real science fiction. Suppose in orbit we build a monorail that encricles the entire earth... a ring at the equator if you will.

On this monorail you run a train in the opposite driection from the orbital direction and then drop the cable down to the car being lifted up by the baloon. Clearly you have the option of matching velocities. So the car gets transfered to the cable and the baloon gets deflated as the cable takes over the lift. In order to counter balence the weight of the train, the monorail track has counterwieghts and enough strength to actually carry the train and the elevator car.

Then as the car is lifted by the cable the velocity of the train on the monorail is increased to match orbital speeds.

I think all can see the problems with this system. The train must travel at a speed of about 25,000 miles per hour in order to match the speed of the elevator car and even in space it might be difficult to build a train that can handle this velocity difference relative to its track.

However - perhaps using maglev this can be done. If so the kinetic energy of the train can be transfered to the monorail and once the elevator car has been picked up the kinetic energy of the monorail can be recovered to accelerate the elevator car and the train. Essentually the train just brakes and we would need a big capacitor that we can feed the energy into.

Aside from the idea that the monorail is over 26,000 miles long, maybe the physics will work.

Also, with a properly designed rail gun we might be able to launch the building materials into space so there might be some way to build the monorail without expensive rocket systems.

Science fiction? of course this is. IMHO so is a space elevator.

Re:where does the kinetic energy come from?

[Teancum]

If you are talking about a "capacitor" that would both store and dissapate energy, it would be the elevator cabling itself. Presumably, based on the design of the cabling, you could have several "cars" going both up and down the length.

This is where the tensile strength is so important (and the real technology killer item here if this is going to work). The cable has to be able to handle not only generalized stresses, but also localized stresses from individual cars. Portions of the cable would be moving either towards the earth's rotation or against it (depending on where the imbalence is occuring. In practice, this would have the cable with a "wavy" appearance going up to the end of the cable. The "broker" would have to be at far end of the cable, which would have to add extra delta-v or remove it if the cable got unbalanced too much.

One problem I can see right now is trying to dampen the "waves" that would come from the vehicles going up or down. This is a similar problem that electric utilities have to deal with when you add or remove equipment to the power grid: Extra power has to be generated when more stuff is added to the grid load (like a whole subdivision turning on their air conditioners), so to keep things balanced they have to start back-up generators or open more flood gates at the local hydro plant. Similar problems happen to try and keep the power at a nice 60 cycle sine wave, because some customers (like computer users) have equipment that really makes a mess of that power generation scheme. Other equipment requires that nice simple generation patter, so compensators are in the utility grid to smooth out those rough spots. This is one way to tell what a good electric utility is vs. one who doesn't care (with either situation above.)

This could also be "smoothed out" by giving just a slightly bit more mass to the cabling itself as well, adding redudancy and safety factors as well as allowing for heavier loads.

The real question is if there could be a "Tacoma Narrows" incident with a space elevator?

Re:How Far?

[NoMoreNicksLeft]

Wrong type of strength, and the material is probably too reactive to the high energy of an anti-tank weapon. Tensile strength is how much it resists stretching (and breaking). For armor, you're more worried about how it compresses, and dissipates energy laterally. Also probably failure modes... concrete is rather strong this way, but you don't want it spraying chunks of broken concrete everywhere (metals tend to dent). Keep in mind, I'm a high school dropout and an amateur, so don't flame me too much if I've glossed over things or gotten them wrong. I tend to talk out of my ass alot.

Re:#1 thing not to say about a space elevator cabl

[nutznboltz]

4,564.635.454th Floor -- Ladie's lingerie and gloves.

Going up.

MOD PARENT UP

[exp(pi*sqrt(163))]

I may turn out to be wrong but it ain't flamebait.

Re:How Far?

[njchick]

There is a /slight/ difference in costs between 62 Miles, and 62,000 miles.

Sure, but the 62 miles elevator will be more expensive because it will have to be made out of extremely stiff materials, such as diamonds or ceramic used in Rado watches. The 62000 miles elevator can be flexible because it will be stretched by the Earth rotation.

Mod parent clueless

[maysonl]

The ISS will be obsolete if this thing is built, and humans will ride the thing in massive numbers (stowaways if nobody else), probably to a geosynchronous city.

Insightful, my arse.

Re:Mod parent clueless

[AgentOJ]

Ok, I'll bite for the flamebait, if only to make a single point:

The MIR space station was first manned in 1986/1987 and was in operation until 2001. That's 15 years of almost continuous occupation relying on core technology from the 80's.

The ISS was first manned by a crew in the year 2000, and considering the major technological advances from the technology found in the MIR space station, I feel that it's safe to say that the ISS will still be in use 15 years from now.

If you really want to be pedantic about the whole issue, replace "ISS" with "Whatever the space station in 15 years will be called."

Even if the space elevator is operational in 15 years, I think most people would agree that it would take more than 15 years to work out the kinks in getting a "geosynchronous city" operational.

Re:Mod parent clueless

[Anonymous Coward]

The ISS was obsolete as soon as they made the decision not to complete it. The science/maintenance ratio makes it a waste of space :)

Surely anything usefuk that ISS can accomplish could just as well be accomplished in geosync.

IBM ad circa 2019

[witort]

Where are the space elevators?! I was promised space elevators!!

Linky!!!

[Anonymous Coward]

It's not that hard, people!

http://www.nature.com/nsu/040308/040308-10.html

http://www.technologyreview.com/articles/rnb_04120 4.asp

And just for karma's sake: http://en.wikipedia.org/wiki/Space_elevator

So who's still laughing?

[Saeger]

Arthur C. Clarke is famous for saying that the space elevator "will be built about 10 years after everybody stops laughing," so who's the joker who's still laughing and holding us up an extra 5 years? :)

It's probably the nanotube/nanotech pessimists who are ignorant of the law of accelerating returns.

--

Re:So who's still laughing?

[StrawberryFrog]

Arthur C. Clarke is famous for saying that the space elevator "will be built about 10 years after everybody stops laughing

I thought that "10 years" was a misquotation, so I dug this up via google:

Clarke, who spoke via a satellite link from his home in Sri Lanka, also recalled his earlier remark about the elevator reaching fruition "about 50 years after everybody quits laughing."
He updated that prediction in Santa Fe.
"It will be built about 10 years after everybody stops laughing," Clarke said. "And they've stopped laughing."
http://www.conway.com/ssinsider/snapshot/sf031201. htm

bragging rights

[Requiem]

Imagine the lucky couple who become the first members of the 62000-mile-high club.

Sure, he's an optimist...

[Goonie]

But he's a salesman-scientist trying to convince people to invest in his big idea. Are you going to tell them "We COULD build it in 15 years" or "well, it probably won't happen for 40 because {the military-industrial complex, NASA, them welfare queens takin' all our tax money, the Canadians} won't let it." If you want something to happen, it's a better idea to talk it up rather than down!

Re:Sure, he's an optimist...

[GISGEOLOGYGEEK]

Us Canadians would fully support US efforts to build a space elevator .... so long as your dumbass president doesnt try to convince the world that we have to build it now because the moon people have WMD's and are planning terror attacks with Al-Qaeda based on some rumour he heard on the street.

If he would just give honest open reasons based on facts, instead of outright lies based on false evidence, your friends would be helpful.

We hang back when we see that Dubya is trying to mislead us, leading us into war under false pretense, why don't you open your eyes and do the same?

Nevermind, I see you are still too busy with all that duct tape Dubya scared you into buying awhile back.

#3 thing not to say about a space elevator cable

[gulfan]

#3 Man beside you forgot his deodorant? You're stuck till the next stop! (oh snap, there's only 2 stops)

In other news ...

[spectasaurus]

Professor Frinkley, head of the non-gravitational society, has stated that no-gravity suits are only 15 years and $10 billion away. Upon leaving, Dr Frinkley made us pay for his coffee and donut and asked us for $10 billion more.

K.I.S.S.

[Anonymous Coward]

Personally I think an elevator is jumping the gun. We don't even have a stairway, and already they're talking about putting in an elevator?

The Panama Space Canal

[Mulletproof]

You see, we've done this before... You know, the "monument of engineering in somebody else's country" thing? So where do we build this thingy along the equator??

Let's take a look:

Guatamala
Honduras
Congo
Gabon
Dem. Rep. Congo
Uganda
Kenya
Somalia
Indonesia

Are you fucking kidding me??????

Yes, I can see this one happening in the very near future. Just the places to plant a multi billion dollar space elevator, right? The only country I'd even consider building this thing would be in Singapore, depending on how much equatorial leeway we have to play with. I mean the science is one thing; Great yeah, we have the money and the technology, lets build this mama! But actually breaking ground on this thing is a political nightmare of epic proportions. Stability of the local governement is just as big, if not a bigger issue than "can we build it/how much?"

The fact that the builder is going to want to make money off it once it's built is another huge issue, severely limiting the number of sites. Unless you want to ship all your ultra high-tech parts halfway around the world to, say, Somolia? ...Let alone defending the site from the world village idiots.

Price to build isn't the only thing the government is looking at here and Bradley is a fool if he thinks that's all that's stopping this from moving forward.

Re:The Panama Space Canal

[ddpriest]

Sounds like the earth end would be floating.

"The cable would be attached to a platform on the equator, off the Pacific coast of South America where winds are calm, weather is good and commercial airplane flights are few. The platform would be mobile so the cable could be moved to get out of the path of orbiting satellites."

Re:The Panama Space Canal

[Mulletproof]

But whose coastal waters would those be again? How "offshore" is this thing going to be??? A quagmire any way you look at it, short of annexing a slice of the pacific outright...

Re:The Panama Space Canal

[Anonymous Coward]

Honduras and Guatemala aren't what you're looking for in the western hemisphere, its Ecuador (of course,) Columbia, or Brazil.

Re:The Panama Space Canal

[tgibbs]

You see, we've done this before... You know, the "monument of engineering in somebody else's country" thing? So where do we build this thingy along the equator??

Actually the plan isn't to build it in any country. The proposal is to use a floating platform converted from an oil drilling rig. There's a lot more suitable ocean than land, and an ocean platform could be best situated for good weather, and even moved a bit to dodge larger bits of debris. A platform out in the middle of the open ocean would also be less accessible to terrorists.

Re:The Panama Space Canal

[Anonymous Coward]

Why coastal? Nations only get sovereignty a few miles out. The rest is international waters, can't be annexed by anybody. For various reasons, the thing is going to be based on a giant ship, which will travel around to keep the elevator away from space debris and electrical storms. (It'll be in an area with very low frequency of storms.)

No more a quagmire than cruising around with an aircraft carrier, really. Besides, if it's a long ways offshore, it's easier to defend with said aircraft carrier..

Re:The Panama Space Canal

[TexNex]

One of the best places would be Kwajalein Atoll, Republic of the Marshall Islands, home of the Regan Missile Defense Test Site so the some of the cost has already been taken care of.
At 8 north it's not to far off the equator so another plus. Add to that the lack of any populous areas near it and I'd say we have a winner.

Re:The Panama Space Canal

[RoboRay]

An oil rig? Blah. I figure a retired aircraft carrier would be ideal.

Re:The Panama Space Canal

[IWK]

Let me guess.... American, right?

[..yawn..]

Re:The Panama Space Canal

[mdielmann]

One of the best ways to mitigate the risk of anything is to have redundancy. And one of the biggest costs of doing anything in space is getting stuff there. The obvious solution is to make the priority of the newly-finished space elevator be to supply materials for the next space elevator. This also mitigates risk due to political instability, gives an international flavour, and further reduces cost to space. All of these things have been talked about before by the big visionaries, Arthur C. Clarke (The Fountains of Paradise) and Charles Sheffield (The Web Between the Worlds) among them.

Re:The Panama Space Canal

[valisk]

Well...

There are a number of small British Island dependencies out there, such as Diego Garcia, which are ideally situated (and well defended) for such a venture.

Re:The Panama Space Canal

[Mulletproof]

Hmm.. guess I was under the impression it actually had to be solidly anchored... But if it can float around, sure, why not I guess.

$500,000? At NASA?

[Leebert]

NASA already has given more than $500,000 to study the idea...

That's not all that much money at NASA, it's the equivalent of 2 Full Time Equivalents (FTEs), plus a little bit of equipment to work with.

remind anyone of an old story?

[cliffa3]

elevator sounds like a new tower of Babel...
dang
and just when most everyone was starting to pick up on English.

Cool technology

[unoengborg]

But who will be willing to pay for it. I guess that much of the existing space shuttle technology have been developed with military purposes in mind. That would probably make governments more willing to put money into conventional technology in the name of national security, than into this new and probably more vulnerable elevator.

Another question is, will it really work? Even if each fibre in cable could be almost unbreakable, each fibre need to be very long or you would have a high probability of having all fibres end in one specific place along the cable, creating a weak spot. From what I understand they have had this kind of trouble in deap sea expiditions, and in this project we are talking about much longer distances.

You just know

[bXTr]

some smartassed little kid's gonna push all the buttons.

New extreme sport:

[sentientbeing]

Spacesuited bungee jumping!


Man what a rush.

static electricity

[Anonymous Coward]

Wouldnt such a long cable from space downto earth generate zillions volt of static electricity?

Correction

[GISGEOLOGYGEEK]

'It's not new physics--nothing new has to be discovered, nothing new has to be invented from scratch,'

... except for a light material strong enough to be used for the elevator. Carbon nanotubes on their own are more than strong enough .. BUT there is presently no way to bond them together in sufficient density in a material that could be used for the elevator. Presently light composite polymer carbon nanotube ribbon cable can be made with 1% nanotubes ... 50% is needed. So, we need new physics to discover a polymer matrix from scratch to bond together the nanotubes to make the elevator. Thanks /. for another misleading story.

Re:Correction

[Inominate]

His statement is still correct.

We have the material. It needs refinement, but it exists. It doesn't need to be discovered, no does it need to be invented.

It's like comparing a 386 and a 3ghz pentium. The 386 lacks the power, but it's not such a big step to a current 3ghz processor.

Re:Correction

[GISGEOLOGYGEEK]

Let me say it again since you missed it.

We need some New Physics to Discover from Scratch a New Material that can be used to bond the nanotubes together in sufficient density because NO SUCH THING exists right now.

And, about your 386 analogy ... actually it is a huge step because ohhh a few hundred technologies that allow today's processors to do what they do Did Not Exist when 386's were the best. Even if you could somehow make a 386 run at 3ghz, it would only be able to do maybe 1% of the work that a current 3ghz processor can do.

In other news

[bl8n8r]

Experts are finding drug abuse, particularly crack, is rising in the scientific and technology fields.

yet another Yahoo article appears on Slashdot

[Anonymous Coward]

Guess Slashdot has run out of originality.

Nothing has to be invented?

[jcr]

Excuse me? What kind of materials do we have today that can take that kind of tension?

-jcr

Re:#1 thing not to say about a space elevator cabl

[ari_j]

Did you do the math on that? I'm way too lazy to check, myself. :P

Re:Elevator? Hmmph

[shigelojoe]

And if the Space Escalator breaks, you still have Space Stairs!

"Only 300 million more steps to go... *groan*"

Opps, sorry

[cbdavis]

Your 15Billion bucks was sent to Iraq last week.

But thanks for playing.............

Re:How Far?

[quakemeister]

someone who remembers basic physics please verify or correct me - in order to figure out how far you want to go, you need to balance:
- the total weight of the cable (mass X length X gravity (which decreases over length to zero)
- depending on where your length gets you, you now need to calculate how much mass you need to create enough centripetal force to balance out your cable (+ load) weight.

it seems like the longer the elevator, the necessary counterweight and then corresponding required cable strength goes up pretty fast.

hmm im thinking this gets beyond basic calculations pretty quick with all the variation in gravity all the way up.

The fibers will still be as long as the elevator.

[mosb1000]

The epoxy is only to ensure that the weight is distributed evenly across all the fibers. The vast majority of the tension will be along the elevator vertically, the epoxy will only have to be strong enough to keep the fibers from coming apart horizontally.

only $14k from each slashdotter should do it.

[deathcloset]

that's only $1400 per year for a decade. $116 a month, about $4 a day! if we all just stop eating taco bell one meal a day we can do this! So, who do I make a paypal donation to? who's the leader in carbon nanotube research? I have a big, fat $20 bill with 'C' written all over it! seriously, I do. I wrote it with a marker.

Location, location, location

[Anonymous Coward]

Of course you need to have the ground station near the equator. I predict that the USA will find an excuse to invade and annex Panama in 15 years.

So you mean....

[judowillreturns]

...I've got to endure another 15 years of excited Slashdot stories, cynical responses and general -1 Flamebait crud?

Guatemala and Honduras are not South America

[Anonymous Coward]

Guatemala and Honduras are not South America, and way above the equator anyway.

Re:Guatemala and Honduras are not South America

[Anonymous Coward]

Shoosh. You'll spoil his self righteous indignation and throw his ill-reasoned xenophobia into question.

Re: epoxying nanotubes

[TomRC]

The epoxy doesn't need to be as strong as the nanotubes. All that is necessary is that all the force from the lower of the two overlapped segments be transferred, over the whole overlapped length, to the top segment.

Imagine holding one hair, with a second clinging to it by electrostatic force. As long as they're overlapped "enough" to have the force between them exceed the weight of the second hair, they won't slip.

If you pull the second hair down enough that the net force between the hairs is less than the weight of the second hair, it'll pull away.

So long as the overlapped region is short relative to the un-overlapped length, the strength to weight ratio need not be greatly reduced.

So the idea of epoxying nanotube strands together isn't absurd - but it does need to be proven that enough force can be transferred in a short enough length by that method.

that "too cheap to meter" is entirely possible

[Anonymous Coward]

The thing is, where with any other form of power generation, the people in charge say, "How much do we need to spend to make it safe?" with nuclear, they say, "How much can we spend on making it safer and safer without making the energy cost more than a coal power plant? Hmm... that doesn't sound like enough. Let's spend twice that."

A $10 bn space elevator is possible. It's just that the kind of free hand they'd have to give to the people building it could also produce that "energy too cheap to meter", or rocket ships for $50,000 each that fly to orbit and back on $100 worth of fuel.

In other words, it's possible without a chain of command - where everybody, regardless of technical ability or intelligence or any other sort of qualification, has to be satisfied with the feasibility, safety, and acceptability - up to the elected officials, and through them up to Joe Sixpack, the voter.

It's possible in a society that actually consistently elevates capable men to positions of authority and lets them go ahead with their work.

sniff.. sniff. awww, who did that??!

[binarybum]

I hope we can get legislation to make it a federal offense to fart inside this thing.

charlie and the chocolate factory....

[zlel]

had one of these, no?

Materials Development part is cheap and critical

[billstewart]

Edwards thinks we'll have the right kind of carbon nanotube material Real Soon Now, if he gets his grant for a couple million more bucks of development money. That's dirt cheap - and if he's right, it's such a revolutionary building material for non-space use that commercial companies ought to be pounding on his doorstep to invest. Now, maybe this means that commercial companies are more realistic about his chances of quick success than he is, or maybe he's had his head in the government sand too long to realize that if he's that good he shouldn't need to wait around for government grant money and should be able to go out and raise the seed money quickly and easily.

Carbon nanotubes, if the hype is real, are a much better VC investment than most of what we're still doing in Silicon Valley. So is he real or not?

Cargo's most of the work

[billstewart]

Hauling humans by elevator or rocket is a tradeoff that'll change as the thing gets deployed, but the biggest job for this thing is obviously cargo; any reasonable amount of space construction would have far more mass of stuff than bodies up there. Get an initial construction crew up and keep them there for a while, but they're going to need a lot of building material and then lots of spaceship parts.

Only 10 billion... yeah right.

[PrimeNumber]

According to this site The space shuttle costs are 5 times projected costs even allowing for inflation:

Initial hopes set the cost of each mission in the range of (US)$10 to (US)$20 million. Allowing for inflation, that would equate to about (US)$100 million today. Actual costs have been running (US)$500 million per mission. Turn around time between flights was initially planned to be about two weeks. It now typically takes several months.

So why should we believe the government has mended it inefficient ways and $10 billion estimate is correct?

Personally, I think we would be alot better off to have Burt Rutan get a crack at this first.

Down's much easier - take the express

[billstewart]

Actually, you would leave most of it at the top - it's much easier to get down the quick way, because a landing craft is much simpler than a rocket that has to get up into orbit. So you'd haul a bunch of landing craft up the elevator, and people who want to head back down take the express lander. Not sure if the right design is mostly a parachute or more likely mostly a glider, but it means you don't have to take a long slow trip through the Van Allen Belts - just a quick drop.

Re:Down's much easier - take the express

[uberdave]

That makes no sense. You've got a car that takes people safely up the elevator, and instead of taking that same car safely down the elevator, you want people to get into some sort of landing craft to come down? You realize that that lander will be coming down from orbit. It would need to make a deorbitting burn, have all the heat shielding necessary for re-entry, and suffer from all the risks that a shuttle re-entry suffers from. It's not simply a quick drop in a parachute or glider. As an emergency vector home, it would be fine. But for routine returns, well, the car needs to come down anyways. It might as well come down full rather than empty.

Re:Down's much easier - take the express

[billstewart]

The problem is radiation exposure, which you want to minimize - an extra week's trip means you either need to bring down _lots_ of shielding or else you're increasing your risk. On the other hand, I was assuming that the down elevator would be the same slow speed as the up elevator, which isn't necessarily so.

Re:Down's much easier - take the express

[uberdave]

Are you trying to say that the radiation exposure danger is different on the way down than the way up? Please explain, because the problem looks symmetrical to me. You're travelling through the same region of space over the same time period, just in a different direction. If a shielded car can bring an astronaut up safely through the radiation belts, then why can't it bring an astronaut down safely?

Re:Down's much easier - take the express

[billstewart]

Any exposure is bad unless you've got really heavy amounts of shielding. You get some exposure on the week-long trip up, and some on the week-long trip down, and you could avoid the latter by taking a lander instead. The asymmetry that I'd missed the first time was that you can run the elevator faster going down than going up, if you really don't like taking a lander.

Why don't we mix up our space scenarios?

[Anonymous Coward]

I mean, a few weeks ago it was an article about building three stage balloons to take people into space, the first stage being an enormous balloon remaining at 80,000 feet. People would fly up to this platform (in a balloon), and then take a different type of balloon into earth orbit.

So how about instead of the space elevator coming to the ground, it just comes to 80,000 feet of the ground? (To our floating city above the clouds....)

And why not build a space elevator to go down to the moon or the surface of Mars? Having much less gravity, these would be considerably shorter and be much less challenging technological projects. We need some way to get that helium 3 we will be mining on the moon back to earth, and you can't land a balloon on the moon. (Actually, you could crash land it, but what's the point?)

Is this mod funny material?

Re:Why don't we mix up our space scenarios?

[nusuth]

Is this mod funny material?

Let's see:

And why not build a space elevator to go down to the moon or the surface of Mars? No, I think it is possible to build those elevators with current technology. However first step to leaving Moon and Mars shall be reaching there. And once we do, we will probably use the technology we perfected getting there to leave there.

So how about instead of the space elevator coming to the ground, it just comes to 80,000 feet of the ground?

That makes little sense. 80000 feets is too little to make any difference (0.02% of the cable length). The only good that would come out of that will be better protection against sabotage and perhaps lightnings. On the bad side, you have to deal with docking at 80000 feet.

Re:Why don't we mix up our space scenarios?

[painlord2k]

Actually, the pysic of the Moon Elevators is totally different from the physic of the Earth/Mars elevators: Moon rotation is too slow, so the elevator will don't work, you need to rach and go farter the Lagrange points from the Moon surface. Would be better use rotavator/theter systems or EM mass launcer. The Mars Elevator is possible with the current tecnology (Kevlar is enought to build it) and it would be smaller than the Earth elevator. Look for http://en.wikipedia.org/wiki/Space_elevator

Have none of you heard...

[Esion Modnar]

"Stairway to Heaven"?

Re:#1 thing not to say about a space elevator cabl

[gcaseye6677]

Or worse: The fat sweaty guy next to you cuts a huge fart. Everyone moves to the other side, but it still reeks, and there's still a few hundred thousand miles left to go.

WTF

[Trigulus]

OK I admit I am drunk but I fail to see the significance of 62,000 miles. That's well past geosynchronous orbit and not even close to moon orbit... the way I see it... it would need a constant source of propulsion or it would wind up around the earth! Please somebody enlighten me so I can go to bed.

There is no material strong enough... ever.

[El Camino SS]

I thought I read somewhere that the kinds of pressures that the cable were required to have were so incredible that it surpassed the bonding strength of atoms, so with that in mind, this whole conversation is freaking ridiculous.

Guys, I love the idea, but honestly, this is a physical impossibility.

Around here we follow the rules of physics.

Re:There is no material strong enough... ever.

[aXis100]

Not true, i've read many articles on the strength required, and current carbon nanotube research is within the same order of magniture of required strength or better. We just have to learn how to make a composite cable in bulk.

From Nasa

Fiber materials such as graphite, alumina, and quartz have exhibited tensile strengths greater than 20 GPa...
The desired strength for the space elevator is about 62 GPa...
Carbon nanotube exhibits extraordinary mechanical properties: the estimated tensile strength is 200 Giga-Pascals.

An Oskar grade Anonymous Coward post

[dmanny]

That's Oskar Schindler, of course. I was looking for this line.

what if the thing collapses?

[Anonymous Coward]

KS Robinson has some rather spectacular accounts of an elevator collapse in one of the Mars books (Red or Green), pretty destructive. Is it known whether his portrayal is accurate?

Re:what if the thing collapses?

[NarrMaster]

I believe a swell answer lies here:
slashdot.org

Correcting you ;~)

[StarsAreAlsoFire]

The system steals energy from from the rotation of the earth.

If you don't ever send mass DOWN, then after one billion forty two million seven hundred thousand four hundred and thirty two trips the ride shuts down.

Seriously though: imagine what happens if you spin the proverbial cat-in-the-can around and 'round: if you HAPPEN (oops) to get slack in the line (by, say, 'accidentally' hitting a tree branch), but continue to spin round and 'round at 'X' rpm, the can will SNAP back into its old position, oscilate a bit, then settle out exactly as it was before.

*no cats harmed in the making of this analogy

That's fine but,

[12357bd]

How do we dissasemble one of these 'elevators'?
Without knowing how to dismantle the thing, we hardly can afford to build one.
I still remember some SF novel about the breaking of a space elevator, scary.

is it possible?

[turnin]

62,000 miles elevator on a planet of ~8000 miles diameter.

To be realistic we can't use the total diameter of earth as a base for the elevator ... so let us take 1/4 of the diameter(this also in my view is not a possible figure!) i.e 2000 miles. the ratio between the base to the column(elevator hight) is 1:31 !!

To feel this, let us imagine a 31 feet hight column on a one feet base.... think of wild atmosphere/space. at the center of the earth the speed is zero, as you move to periphery the speed increases and it is ~1000 miles/hr on the outer side of the earth. Now come to our case, the periphery has bee increased to 62000 miles ... what will be speed at the periphery now?!! a column constructed with 1:31 ratio of base to hight will be able to withstand the peripheral speed?

I work 200 feet from the ISR building and...

[glitch23]

their "building" is still being worked on, has been for over a year now. It is oddly shaped and with the roof shaped like an airplane wing (and with the building on top of a hill) I'd say that with a good enough wind it will get to space before the people do (unless of course people are in the building at the time :) ).

Revised estimate

[mdielmann]

Hmm, $10 billion, minus $2.5 million, plus the required political pork...we're only $20 billion from being able to fund this!

For what?

[dtfinch]

What'll cost us 10 years and $10,000,000,000 to build, some crazy extremist will bust down in 10 seconds with $10,000.

There are other uses for CNT

[XNormal]

One point that space elevator advocates always seem to conveniently forget is that carbon nanotube composites will benefit competing technologies, as well.

For example, they would make it much easier to achieve the tankage mass ratios required for a single stage to orbit reusable launch vehicle. Such vehicles are believed to be marginally possible today but CNT composites could easily make them competitive with elevators.

Jordin Kare of LLNL has a nice presentation comparing the costs of space elevators to other potential technologies. The bottom line is that the elevator is not necessarily cheaper and has much larger up-front costs before the first payload goes up.

Using space elevators as a justification for investments in CNT composite technology is propaganda.

sorry

[Anonymous Coward]

but 15 years is a realistic estimate for when we could have one up.

Sorry, dude, but she ain't gonna wait that long.

Anti-gravity

[adius]

All we need is a device that defies gravity. I think it is just a matter of time till someone figures it out. Once it is available, we can just hover towards the sky than use these bulky and outdated contraptions.

Re:#1 thing not to say about a space elevator cabl

[Wolfrider]

Steven Tyler (laughs): "I'll wait for the other one."

http://www.cool-lyrics-site.com/Love_in_an_Eleva to r_Lyrics.html

Can we do it?

[Anonymous Coward]

Can we really do it in 15 years? Yes, we really can. The trouble is the world is too full of irrational people. If everybody in the world sat down and said, "Hey, this is a worthwhile goal, let's work towards it (even if my part is just to make food, or clothing, or houses for the engineers who are actually making it, so long as we recognize it is a world wide goal)," then we could do it. If every scientist and engineer making new weapons to kill one another, designing new bigger and "better" SUVs, or really just doing anything less important, then we could easily overcome the technological hurdles. If every super rich person realized that funding something like this is more important than piling up money in an attempt to console themselves over the tragedy that their phallus isn't 18 inches long, and if all the governments stopped wasting billions on mismanaged beaurocratic progams, wars, and locking up the week end pot head, then we would have the money. Unfortunately, this will never happen on any appreciable scale. Overall people are too selfish, stupid, shortsighted, and just generally lacking in the ability to think comprehensively that reasonable, meaningful cooperation doesn't work on any noticable scale. If we ever build a space elevator it will be because the small steps of technology will have brought us to the point where it won't be all that hard to do, not from some grand push.

To sum it up, we have the mental power, the man power, and the resources to do this in 15 years. What we do not have is the focus or the resolve.

Re:no god this can be appening!!! -- Conspiracy

[Anonymous Coward]

No one is riding this -- it is an advanced demonstration of the physics 101 experiment where you're spinning on a chair and you slow down when you stick your feet out. Pretty soon we'll be seeing today's Dr. Evil on T.V. sitting next to the "Space Elevator/Destroyer 2015" demanding one trillion dollars otherwise he'll raise the counterweight, making days longer and time slower -- thus throwing off the balance of the universe!

Oh yeah!

[Anonymous Coward]

This is a really good idea! But where the hell are we going to take this stupid elevator in the first place? To the landing point that already exists on the moon, or venus or even mars for that matter? Who gives a shit about the elevator when there is nothing built on other planets to cater for this stupid elevator in the first place!

people are dumb...

[eathan13]

so this counterweight swinging around out there pulling the elevator cable taught... any chance that might stretch the cable? how much and how does that effect the plan?

wait i'm sorry, we don't know, 'cause even the cable is still a work in progress.

all that aside, where the crap is this elevator even going?

did i read 62,000 miles right? show me something over 6.2 miles long without a crack...

my prediction, the thing will break, break, break and maintenance crews will be crawling their way up 30 some thousand miles to sort it out. sounds dead fun...

could it be done? maybe. should it be tried? what's the point?

If Bradley can see one...

[rixstep]

then I can see him going up in it.

Bye, Bradley.

Hey and what are we expecting to see then anyway? Suicides riding to the top floor to jump off the roof?

Whoa.

arthur c clarke, 3001 ?

[Anonymous Coward]

buckminster fullerene?

recouping 90% of the energy used to lift materials into orbit due to gravity...

and honestly - we're all new to this, so does anyone really know till we try?

Oh great...

[Tim Browse]

So in about 10 years time, we'll all be speaking different languages.

(I can wait...)

Re: epoxying nanotubes

[nusuth]

It is absurd. If epoxy cannot be used alone, it means that attraction between its own molecules or bonds of ploymer chain cannot withstand tension elevator experiences. Which means that electrostatic force were an accurate analogy, the electrons would have fallen down from atoms, let alone lift anything else. If the electrostatic force can't overcome gravity even if full length of hairs overlap, how would it possibly hold two hairs together when they partially overlap?

Re:The fibers will still be as long as the elevato

[nusuth]

Will they be able to produce each tube as long as the cable itself? If not, they will have to glue them together to withstand vertical tension too. Even if they could make thousands of miles long strands, since the cable thickness isn't constant, it will be required to glue strands at some regions.

They will have to take off their pink glasses if they want any more progress. Chemically binding tubes with each other should be possible. Tangling tubes and using glue to avoid untangling should be possible. Neither option would have the same weight per tensile strength ratio. They might work, perhaps they won't. In contrast, their proposal -as it stands- cannot possibly work.

Re:Elevator? Hmmph

[Anonymous Coward]

Just you parents make sure your kids aren't wearing loose jeans on the escalator!

Better jeans than a skirt. Think about it - every creep with an observatory and a 200 inch reflector will be taking upskirt photos ... :)

Cheap way to access space? Not!

[nusuth]

Given rockets spend tens of thousand dollars for reaching geosynchronous orbit the space elevators a few hundreds of dollars per kilogram sounds good...until you compare it with 10 cents per kilogram of Orion. P George Dyson's "Project Orion" is a great book on the subject. http://en.wikipedia.org/wiki/Orion_project is a good introduction.

With the elevator, forget the ISS

[Inominate]

Why bother with ISS once a space elevator is operating?

While it would be very difficult to transfer cargo to things in low earth orbit, it would make it relativly easy to establish a new space station at a geosynch orbit.

G-forces

[Inominate]

Out of curiousity,
Any idea what the G-forces would be at the end of the tether? Would it be enough to support a low gravity environment for future astronauts?

Re:G-forces

[Bob Munck]

Very low. Even at the end of a 100,000 km tether, the effective gravity is -0.0538 g. Actually, centripetal acceleration due to the rotation of the Earth is -0.0574 g and Earth's gravity is 0.003596 g. You're much better off using this wonderful carbon nanotube ribbon material to connect two (or more) habitats and spin them around each other, with the whole construct orbiting near the elevator at GEO.

Why not skip the cable altogether?

[mrjb]

One of the biggest obstacles in building the space elevator seems to be making the cable (plus overcoming problems that go with it: stretching, counterweight, etc.) Obviously the cable causes a scalability problem, so why not skip the cable completely? Unless I completely missed the point, they're gonna have to build some huge tower to pull up the elevator. Why not 'simply' build a tower with a jagged inside, and let the cabin have cogwheels and drive up with its own engine? The elevator would only have to carry its own weight rather than needing an engine that can also lift the weight of the cable. Plus, such a 'wireless' space elevator would allow several trips up simultaneously, which probably would make it economically more feasable. Is it me that hasn't grasped the concept? It seems to me that the approach that they're going for is ridiculously impractical. Or do they somehow envision an elevator without a tower?

Re:Why not skip the cable altogether?

[SouperDouper]

I think you are missing the concept of how this will work, so I'll do what I can to elaborate. The elevator does not have to lift the weight of the cable, the cable is simply the device that the space-bound vehicle will climb up. Imagine it as the rope in gym class: You only have to carry up your own weight, not the weight of the rope, and instead of having it attached to the ceiling, it is being held out there like if you were to have a rope with a weight on the end that you were spinning around in a circle. It capitalizes on the fact that the earth is spinning and it will stay out there even with the "elevator" going up or down.

Re:Why not skip the cable altogether?

[GISGEOLOGYGEEK]

There is no tower, and exactly how do you think a tower 62,000 km high could be built?

at the ground, the cable is attached to a platform that can be moved. It must be at or near the equator.

at the top, there is a large counter weight in geosynchronous orbit around the earth so that it stays above the same point over the earth's surface. The counterweight want's to fly off into space, the weight of the cable keep's it there (not the connection with the ground)

effectively the entire system, cable and all is in orbit around the earth. It's a satellite with a cable that hits the ground.

You can climb up the cable. This is much more cheap and efficient that launching a rocket.

The cable material is so strong that it will only weigh about 26pounds per MILE of cable.

The base of the cable can be moved to protect it from storms. other sections can be moved to protect it from space junk.

Re:#1 thing not to say about a space elevator cabl

[Mudcathi]

#3: In case of fire, BREAK GLASS

Sounds Like Fun...

[NoThumbsForMe]

I'd like to drop a penny on someone's car from atop that sucker...

Re:Sounds Like Fun...

[NoThumbsForMe]

oh, I forgot the *sarcasm*

how about a space gym rope?

[cks3]

couldn't you just run a really long line (made out of something a bit more durable than rope) with knots in it, and tie one end to the Cape and the other to the Space Station?

I mean, sure, totally useless, but, man, oh man would it make for an excitingly boring extreme sport (in the same ways that golf is exciting). Call the game: Xtreme Climbing: Better than Everest!

ANNOUNCER: "Billy Bob had made it all the way to the one mile mark on the space rope, but a strong wind and bolt of lightning looks to have just knocked him to his death."
ANNOUNCER #2: "So much for his claims that his 'lucky' Bowie knife would protect him from lightning!"
ANNOUNCER: "Ouch!"

Sigh

[Anonymous Coward]

I'm a bit disappointed in your ability to look at the facts objectively. Fusion research has come a long way since the old days, you don't believe me? Then why are they busy to build a final prototype reactor design that they hope once the bugs are worked out can be used as a base for building actual commercial reactors. That wouldn't be very sensible if your research was going nowhere.

As for nanotubes, you are ofcourse right that they arn't better then current best carbon fibers. However, but then none of those fibers were suddenly perfectioned and as strong as they are now either. Such things are done in incremental improvements.

Considering thus that a year ago noone could pretty much make a few kilometer long nanotube fiber, and they can now seems to be considerable progress in and of it's own. And to be honest this first design really is very crude, so it wouldn't be unreasonable to expect that with some more years, and a few design generations further along, that nanotube cables could be made much more strong then they are now. Perhaps even beyond those of other carbon fibers. The money for the research is certaintly there in anycase, cause ultra strong fibers like that would have many uses, so if it can be done, it will be.

Quickshot

Re:$500,000? At NASA?

[craXORjack]

Or one Part Time Equivalent, a couple of co-op students, and the mess of junk left over from building that emergency air filter on the Apollo 13.

Suddenly, terrorists' #1 target!

[Anonymous Coward]

Oh crap, Mr. President - we never saw this one coming (due to bad intelligence).

Center of mass NOT at GEO.

[TheMadReaper]

"Thirdly, 60000 miles? Geosynchronous orbit is at 42000km from the centre of earth, how the hell are they going to keep the "weight" where it's supposed to be? Rockets? Unless they manage to keep the centre of mass at 42000 km I don't think it's possible, and you'll end up with 60000 miles of expensive ribbon wrapped around earth (2.5 rounds) and a small crater where the "weight" met earth."

People commonly believe that the center of mass of the elevator has to be at geosynchronous altitude because it is rotating synchronously with the Earth. This idea is simply wrong. For example, most Slashdot readers are currently rotating synchronously with the Earth. Not one of them is at geosynchronous altitude. In the case of the Slashdot reader, he (she?) does not need to be at GEO simply because he is not in orbit. His chair is pushing him up. The elevator, also, is not in orbit, as it is attached on one end to the ground. In the case of the elevator, the ground will be pulling down on the elevator (this is necessary if you want to be able to climb up the elevator into space). So the elevator is not in orbit, there is no reason to expect its center of mass to be at GEO.

But in fact, the idea of its center of mass being at GEO is even wronger than that. Indeed, suppose that the elevator was not attached to the ground. In that case, the elevator would be in orbit, but it would certainly not be a point mass. Therefore, the orbital rules that most people are familiar with (Kepler's laws, etc) do not apply. Because Earth's gravity decreases slower and slower with altitude (it is a convex function), the center of mass would have to be beyond GEO for a geosynchronous orbit. I've got a little more detail on this on my web page.

Payload of 13 tons?

[thefastrunner]

The article talks of a cable about 90 cm in diameter, which would have a mass of roughly 1 ton per meter of length (if the density is about 1.6 times water density). With a length of 100 000 km, the total mass is about 100 Million tons. Why would it fail with a load of more than 13 tons?

Re:Payload of 13 tons?

[Bob Munck]

90 cm in width, "thinner than a piece of paper" (actually, about 10 microns) thick. Your calculations are off by about five orders of magnitude. Reading is a skill.

Re:Elevator? Hmmph

[Anonymous Coward]

Hey, I wonder where this Escalator to Nowhere goes to, hmmm whoooaoaaaaaaaaaaa SPLAT!

Re: epoxying nanotubes

[TomRC]

The thing you're missing is that the force is spread over a much larger area. I.e between joints, the weight of the elevator is supported solely in the thin cross-section of the ribbon.

But the area between two sections of ribbon overlapped is vastly greater - so the weight/stress/force per unit area is much lower. That means that the force acting to hold any unit area of ribbon together need not be anywhere near as great.

The real question is whether the epoxied segments can narrow enough and far enough apart to avoid adding significantly to the elevator's weight, and whether the epoxied joints can withstand the conditions the elevator is exposed to over time.

Bah

[Tim Browse]

I knew no-one would get it.

Joke, Joyce...

[Goonie]

Three pertinent facts:

• I was joking - "Blame Canada, Blame Canada, with their beady little eyes...". I was listing everybody's favourite conspiracy theories as to why stuff like this doesn't get funded.
• I think Bush is a dangerous moron and detest my government for going to war in Iraq on the basis of lies and distortions.
• I'm an Aussie.

Does that cover it?

Re:The fibers will still be as long as the elevato

[fredmosby]

Fibers refers to groups of nanotubes all pointing the same direction that are held together by vanderwaals bonds. If the tubes are manufactured long enough the vanderwaals forces between the tubes (which are normally week) will be strong enough to hold the tubes together with the strength required for the elevator.

The elevator design calls for one thin ribbon composed of carbon nano tube fiber to be deployed from orbit. After the initial ribbon is put up climbers will travel up the elevator adding more layers as they go to make the elevator large enough to carry a 20 ton payload. The epoxy is required to hold the layers together.

Fibers

[mosb1000]

How long do you think the fibers in rope are? I can guarantee that that 50 ft cotton rope does not have 50 ft long fibers. The Vanderwaals forces between the individual fibers, when acting over the whole length of the fibers, holds them together more strongly than the individual carbon-carbon bonds would. There is no reason to explore chemically bonding the tubes.

Re:Fibers

[nusuth]

How long do you think the fibers in rope are? I can guarantee that that 50 ft cotton rope does not have 50 ft long fibers.

Sure, but nobody says the tensile strength of a cotton rope is almost the same as a cotton fiber.

The Vanderwaals forces between the individual fibers, when acting over the whole length of the fibers, holds them together more strongly than the individual carbon-carbon bonds would.

If your point is when fibers are strongly held together, the cable, rope, whatever is almost as strong as individual fibers even if fibers themselves are very short, I get it.

The space elevator is ALREADY obsolete

[alizard]

We're a lot closer to solving the problems involved with the blimp technology discussed here not too long ago. More cost effective, far closer to reality, a lot safer (YOU want to be around that 10,000 mile ribbon if it snaps?), doesn't require that we figure out how to solve a shitload of CNT-related manufacturing problems involved in building the physical elevator structure, and we know how to build blimps.

The Space Elevator was a great dream.

Let it die and let's start putting real stuff into space for $250/ton (LEO).

Energy from eastward force at cable base

[Adam J. Richter]

I believe that as the elevator car would climb the cable, it would have the effect of tugging the cable west slightly, giving the cable a slight westward kink where the car is.

Centripetal acceleration would work to straighten out the cable again, pulling the car east and rest of the cable west slightly. The bottom of the cable would be pushed toward the west slightly, which would be resisted by the attachment of the base to the ground, the net result being that the base would be providing an eastward acceleration to the cable, infinitesimally slowing the rotation of Earth.

The top of the cable would drift east, but centripetal acceleration would pull it straight too, again resulting in a westward tug on bottom of the cable.

Of course, there is no way for the cable to pull westward if it is going perfectly straight up, so I would expect the cable to gradually lean westward until its pull from the base had enough of a westward vector to compensate. I think the angle would be very slight. Here is a rough calculation.

Let's say the elevator car will climb 22,300 miles to geosync orbit at 22.3 miles/hour, which will take 1,000 hours (more than a month). During this time, the car's horizontal velocity will increase to 8,000 meters/second. So, every hour, the car needs to increase its eastward velocity by 8 meters/second, just to remain "stationary" from the standpoint of an observer on the Earth's (rotating) surface. 8 meters/sec/hour of acceleration is .002 meter/sec/sec acceleration. Let's say the elevator car weighs 1000 kg. The eastward force needed would be 1000kg * .002 meters/sec^2 = 2 kg/m/sec. (2 Newtons), about the force that gravity at the earth's surface exerts on a 200 gram weight.

Let's say the cable is angled at a 1:100 grade (that is, about 1 degree from vertical), so that going 100 meters up the cable also takes you 1 meter west. Pulling the cable from the bottom with a force of 200.001 Newtons would give it a downward force of 200 Newtons (which would be counter balanced by the counterweight of the space tether being slightly farther out) and the eastward force of the required 2 Newtons. 200.001 Newtons is approximately the force of gravity on a 20 kilogram weight.

So, even with just a 1 degree westward slant, I think the force needed to provide the necessary horizontal acceleration would be very small.

However, please evaluate this estimate with caution. I'm just doing it on the fly and I could have made a substantial error somewhere.

ROFLCOPTER

[Obscenity]

this is a ascii sword:


(o)==(::::::::;:;:;:;>

This should be a priority

[Lours]

Even if some assumptions made are probably a bit exagerated, the benefits from using a space elevator would greatly offset the costs. As a matter of facts the costs mentionned are much lower than many other space projects ones even if multiplied by some "security margin" factor.

Another major benefit would be a huge decrease in environmental stress due to space travel.
We tend to forget it but sending ships to space represents an enormous amount of greenhouse gases emissions. This still represents a small fraction of all emissions, but as space traffic increases it might become a not so neglectable cause of global warming. If you look at spaceship one first success it's quite obvious space traffic might increase rapidly.

Given the incredible ratio of greenhouse gases emissions per kilogram of matter "displaced" in conventional space journeys, this simply would not be suitable.

I haven't made any calculations yet, but I wouldn't be surprised if it would become bigger than the air traffic emissions which themselves are an increasing source of concern amongst the scientific community because of their also very high ratio of emissions per kilogram of matter transported.

I guess that if we want space travel and a non hostile climate at the same time, then it's quite time we begin building this space elevator.
It's such a win-win game move that I wonder why no more money was put into research for so many years...

Two Corrections

[MikShapi]

One - an update on what you said - composites have already been made with 5% (a one-mile-stretch IIRC) as of March 2003 when the NIAC phase II paper was written. 25% was talked about here on slashdot a few months back, I'm too lazy to go look up the link. These things are developing rapidly, and a lot of materials labs in universities and corps all over the world are very very busy on it, and backed by very intensive funding (think billions if not tens of billions).

Second, I think you misunderstand the difference between evolution and revolution. Let's take hard-drives for an example. Evolving a circa-1990 40Meg HD into a current 400Gig one is evolution. It required some "minor" revolutions like pixie dust, but all in all it was a process of "find bottleneck, fix, repeat". Nanostorage like IBM's millepede is revolution. It does not include employing engineers to overcome technical hurdles in the "we can't cram more gigs on this platter". It involves canning the technology and coming up with something entirely new.

When you're after evolution, you know where you're headed, you just have to figure out how to get there.

When you're after revolution, you need to figure out where you want to go first.

Space Elevators require evolution in material sciences, and the 386 example was a very good one. We know what we want to do, we just need to figure out the "how" bit. And if the last 20 years taught us anything, it's that we will.

Re:Problems

[A55M0NKEY]

I don't pretend to understand why, but I read somewhere that the minimum energy path for a stretched ribbon leading from the ground to geosynchronous orbit is not a straight line but a spiral. ( maybe someone in the know about this could elaborate. ) But a spiral is a longer path than a straight line, and so would weigh more in terms of ribbon...

An alternative...

[DJdeli]

http://www.spacetether.com/ Another suggestion is to make a long cable that hangs in free air, from a station in a GEO altitude to a drop towards suborbital space. So it will be dangling around 100km or so above the ground. Since it's not anchored to the earth, you can probably skimp a bit on the material's strength of the tether. A first-stage rocket will deliver the payload, which will be taken by the tether when it 'docks' with the spacecraft. The only issue I see is that the 'hangtime' of being in suborbit should be long enough to complete the procedure, and it would take some work into getting the craft going at the same speed as the tether in orbit.

This reminds of South Parks

[pinkstuff]

Ladder to heaven...

Re:Spiral

[reezle]

Yeah, that's what I picture every time I think about it too hard, too....

(I'd love to hear one of those explanations that makes a person say 'Doooh!")