Going Up? 132
An AC points us to this article about the space elevator concept, once solely the realm of science fiction but now coming a bit closer to reality. The main problem seems to be the lack of some material with the ludicrous tensile strength required. Oh, and an asteroid to anchor it. And the willpower to actually build it. Check out the slashdot discussion of an earlier spacescience.com article on this idea as well.
Re:What's the american degree for -1? (Score:1)
Although in reality it would seem pretty magical. Realize the following: anything on the bottom half of the cable would be pulled "down" to the earth, and anything on the top half would be pulled "out". Which means that whichever way you travel, halfway you'll be expending energy move, and the other half you can be _storing_ energy as you brake.
The result: if you send the "elevator car" up in a rocket and latch it onto the middle first, the only power you'll ever need for this thing is to compensate for friction, engine inefficiency, and differences between mass lifted and mass lowered. Which, while still a lot, is still a hell of a lot less than doing it the hard way..
The other neat thing: you can put a massive space station on the middle and/or end of the tether for relatively cheap, since lugging the materials over is almost free compared to the prices of lifting it by rocket. I've heard dreams of orbital refueling stations (for trips further out), orbital resorts, whole cities up there...Plus: parts are less expensive because a) they can be quickly and cheaply replaced and b) they can be cheaper to make because its easy to use redundant units that are, individually, less foolproof than the ones used in current space endeavors.
The caveat: first we have to figure out how to build the damn tether, then we have to actually do it and test it, then someone's gotta pay to set it up, then someone's go to actually go DO it.
Smaller versions wouldn't be AS cool, but they'd still be a godsend for all things space-related.
Re:Silly question about vacuums (Score:2)
I used to think about this when I was a kid, not knowing too much about how the atmosphere stayed where it was.
Nah, a big tube into space wouldn't leak out our atmosphere simply cause gravity keeps it in place.
Zero Kelvin
neux.org
Been There... (Score:2)
Thank you.
-- Patrick Bateman, Esq.
Re:What's the american degree for -1? (Score:1)
Ergo, the cable is under tension all the time and has no chance to develop a knot.
Regards, Ulli
Floating platforms. (Score:2)
How about the 1st step going to a platform supported by a cluster of blimps that will drift a little with the wind, but only as much as the fans let it. This platform will nead refueling by conventional means. No bigy.
Above that you have another platform in the stratusphare kept stable by jets.
And so on ontil you get out to the last haul into orbit.
breaking it up this way achives several things.
#1 if it falls it will just be a part of it. Dangerus but a lot less so.
#2 It should be more stable.
#3 It brings it somewhere within sanity. I.e. We could build some of these stages already.
#4 when there is a failure somewhere on the elevator there is usualy a stop so not everyone will be left dangling on the wire. Only a few
This 31 mile tower is ridiculus. For now. A few baloons hovering at 31 miles up is not however. Ask your local metrologist.
PS: Be carefull with how the baloons are constructed. We don't want them floating to high, deflating, faling or exploding.
Huh? (Score:2)
First of all, Storrs-Hall just described a "mass driver", but one propped up on a 100km high tower for God knows what reason. Which proves:
He doesn't know anything about orbital mechanics, but just thinks you need to "point up to get into space". Well, that's probably unfair; he at least got orbital velocity about right.
He certainly doesn't know anything about mechanical engineering, or he'd realize that making a 100km structure that will support tension may be possible, but making one that won't buckle under compression is ridiculous. Buckytubes may have a hundred times the tensile strength of steel, but they still bend real easy...
Who modded this up? (Score:2)
Don't take this the wrong way: those are all valid questions to ask, I don't think they should be moderated down, I hope they all get accurate responses, and I hope the responses get moderated up. Ignorance is correctable, and the right way to correct it is by asking serious questions.
But could you imagine this kind of thing happening in a computer science story? Would someone who asked "Won't Lunix let the hackers steal my computer cause it's open source?" get stamped with +1, insightful?
Ok, done ranting now. On to your question.
Serious question: Wouldn't such a thing affect the earth orbit?
Quick answer: Yes, but not so you'd notice.
Building the beanstalk, if it were done with asteroidal materials, would add mass, angular momentum, and an increased moment of inertia to the Earth. Depending on how the asteroid was captured, this could raise the earth's orbit slightly, but would leave the rotational period (length of a day) unchanged. Launching interplanetary vehicles from the beanstalk would remove angular momentum (and a little mass) from the system, slowing the rate of a day slightly.
If the beanstalk was built with terrestrial materials (building one thread first and hauling the rest up on that), it would increase the moment of inertia of the planet-beanstalk system slightly, without adding any angular momentum. Again, the day would be slowed slightly.
But, the key word here is "slightly". By slightly I don't mean days that are one second longer, I mean days that are (1 + ~10*(mass of beanstalk / mass of earth), which works out to something like 100 picoseconds, longer. Use the beanstalk to launch continual interplanetary payloads for a few millenia, and maybe we'll slow the rotation of the earth down by a microsecond. This is all back-of-the-napkin arithmetic, of course, but if my conclusions are too optimistic by a factor of a thousand I'm still not nervous.
More attainable orbits (Score:2)
Almost correct; the only point where you can drop off into a circular orbit is at GEO; there's a huge range of hyperbolic orbits you can get into (well, hyperbolic w.r.t. the Earth; enough to take you to the inner planets at least) by dropping off the tower above GEO, and a range of elliptical orbits (including one with perigee in the upper atmosphere, making aerobraking into equatorial LEO a cheap possiblity) you can get to by dropping off the tower below GEO.
Throw in some high efficiency rockets (ion engines, plasma rockets - all the sorts of things you can't use on a launch vehicle because they're too low thrust), and you could get into any Earth orbit with a lot more payload, a lot cheaper than with a conventional rocket.
Or perhaps I should say marginally cheaper; as the amortization of the original construction cost should be considered. Of course, building this thing means manufacturing thousands of tons of buckytubes, each thousands of kilometers long. IIRC, current buckytube manufacturing is on the order of $2000 a gram, for micrometer-sized things that might be useful in electronics, MEMS, or nanotech, but certainly wouldn't be as a structural material. We've still got a little technology to research...
You've got it all backwards (Score:4)
How about matter? I'll spare you the numbers, but it wouldn't take a very large asteroid to supply our entire civilization's structural metal requirements for centuries, and to provide enough mass of everything else to make the phrase "precious metal" an oxymoron.
There's a nice Kuro5hin discussion [kuro5hin.org] going on right now about overpopulation, including the question of what is a "sustainable" population for humanity. The answer isn't encouraging; our fossil fuels won't be around in a few centuries, our fissionable metals will give us a few centuries more... and then what? Solar power? Not concentrated enough, unless you've got a plan to reduce our population 10-fold, or pull in extra power from space. Fusion? That's better (assuming we get it working eventually), but then you run into the problem that the cleanest fusion fuel, He3, only exists in quantity on the Moon and outer planets. Even if you don't see the value of going into space to support life there, eventually we'll want to leave this planet to better support life here.
The solar system has the resources to support quintillions of people; unfortunately for us an insignificant fraction of those resources happen to be on Earth.
An elevator to nowhere. Imagine how silly it'd look.
So anyway, like I said, you've got it exactly backwards. It would be an elevator to everywhere.
Re:Tensile strength huh? (Score:1)
high shear stress (Score:2)
Hope no one here will be next NASA admin (Score:2)
But your COLLOSSAL lack of physics is, for me, extraordinary. It's just fantastic to see how people go by things like "bringing pieces of Space to Earth", "elevators". How you can forget that Gravity decays at the square of the distance? Do you know what is angular momentum? And how can you dare to think about something pushing this elevator up in vacuum, by itself. Hey, as anyone forget Newton's Third Law? Sorry to be so flamously bitter, but do they still teach it on school?
And what about friction? The stuff is there and no one will kick it out...
And some people come here moderate my comments to 1 while pushing other weird fantasies up? People give me a break. If anyone of these will call himself a Space Geek, then please get to the open and look at that damn Space. Look at it and then look at your own feet. Saw them? You are bound to this piece of dirt. And this damn piece of dirt will be you damn home and grave because you don't know a thing about the world you live in. Like 1000 years ago, you are still a serv of your own ignorance. And you are cursed to be so because you wish more for your feet than for yourself...
Re:Always wondered... (Score:2)
And with regard to the vacuum question, what do you think stops our atmosphere from disappearing into the vacuum of space at the moment? Why, gravity of course (and a little protection from the solar wind courtesy of our magnetic field).
What we're lacking (Score:2)
We lack the materials science to build it, the transportation science to obtain the counter-weight, and the funds to make it all happen.
We've got everything else, though. We're home-free.
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Re:Huh? (Score:1)
The reason is that, at that altitude, you're out of the atmosphere so you don't have to deal with air resistance.
He doesn't know anything about orbital mechanics, but just thinks you need to "point up to get into space".
You are critiquing some other proposal with which I am unfamiliar. I have heard of variations where the linear induction motor runs up the side of a mountain (perhaps this is where you got the "point up" idea) over vastly shorter distances, and clearly this is quite stupid. But obviously you didn't follow the link and you haven't read the proposal under discussion here. The platform's upper surface is horizontal; over 300 km it picks up some curvature. It is consistent with a circular low-earth orbit. Perhaps you've heard of these. They are used extensively by satellites.
J. Storrs-Hall's space ramp (Score:2)
The space ramp is about 100 km high and 300 km long, with a linear induction motor running its length. You take an elevator up to one end, hop on the induction motor, and get accelerated at 10 G for about 80 seconds. This puts you in low-earth orbit, at an amortized cost of 42 cents per kg. Prior to amortization, you'd be paying about a buck a kilogram. The cost for space shuttle launches is about $10K per kilogram.
Re:There has to be a practical reason... (Score:1)
Solve world hunger, tell no one. (Score:2)
Do you need an asteroid? (Score:1)
As far as I can tell, this scenarion doesn't require latching on to an asteroid. Now, it may be that the tether needs to extend a million miles into space to counteract the gravity.
Silly question about vacuums (Score:1)
Just a silly question.
Always wondered... (Score:2)
But wouldn't all the elevations below that be in faster orbits? Even if it had the tensile strength to survive, wouldn't it "stand" with one heck of a gimp in it?
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Re:Too dangerous (Score:1)
Re:Too dangerous (Score:1)
Re:What's the american degree for -1? (Score:2)
By the way, my wife's an oceanographer, and they sometimes deploy experiments on cables that can develop knots which occupy a volume larger than the ship deploying them (the technical term for such as knot is a "wuzzle"). Unless you could keep the series of long lines you would need to hoist the final tether taught and unbroken, you could end up with a knot the size of a large city. If the line were made of an ultra-durable material you could have a very interesting situation on your hands.
Re:What's the american degree for -1? (Score:2)
Re:Changing earth orbit (Score:1)
Dislaimer: This may be bollux. But maybe not.
Re:What's the american degree for -1? (Score:1)
Re:What's the american degree for -1? (Score:2)
This will cause the cable to be under tremendous stress; the satellite pulls it into space while the earth pulls it back. I'm not an expert, but I conclude from this that in the middle of the cable the stress on the cable will be more than twice earth's gravity pulling on half the cable....e.g. if the cable has to be 20000km long and it is 10 grams per meter, it would be 100000 kilograms weight hanging from the cable...and an equal force the other direction. That makes a force equal to the gravity on 200000 kilograms...nice:)
Experts: please correct me if I'm wrong.
lo, forsooth, we *did* do this one at least;) (Score:1)
Maybe Slashdot will even do a story on it...
I wait with herring baited breath"
You mean like this?
http://slashdot.org/article.pl?sid=00/12/16/184
timothy
Re:Hope no one here will be next NASA admin (Score:2)
Do the orbital mechanics. Is it possible to have a tether from past-geosynch orbit down to the Earth, with its center of mass at geosynch? -- Yes, it is. We are aware of no fundamental laws of the cosmos which forbid this. Is it easy to do this? -- Yes, it is, provided that your materials science is suitably advanced. Is our materials science that advanced? -- No, not yet.
Friction really isn't all that much of a problem. Why? Because the most atmospheric friction you get is in the first 75km, and in the first 75km the tether is essentially at rest with respect to the Earth. You don't say "this vase that's sitting on my desk suffers friction losses," do you? No, because friction is associated with movement.
Insofar as propulsion, in case you haven't noticed, we're living on a huge magnet. We're going to have a tether made of electrically-conductive carbon going up to geosynchronous orbit. I don't know about what they taught you in school, but at Cornell they taught me that if you move an electrically-conductive material through a magnetic field, an electric current is induced in the material.
This means that there are megawatts of power available for the taking, entirely as a fringe benefit of having the tether. That electricity can then be used to propel the elevator up the tether.
In short, Ek, I think you're really wrong here. Nothing in physics says this is impossible; in fact, physics says it's easy, given the right materials science.
Added bonus... (Score:1)
Re:OTIS company to perform feasability tests (Score:1)
i think mir might be on the groud floor soon anyway
Re:Silly question about vacuums (Score:1)
Re:Cool! (Score:1)
Not per se, the problem is that nanotubes don't stick to one another very well, and the longest ones are only around 100 microns long. You can get around the length if you can braid them together, but they don't stick together unless they're long enough...kind of a catch-22, at least until we learn how to make longer nanotubes.
Re:Too dangerous (Score:1)
Actually if it is "shot down," it will probably be cut by weapons launched from earth's surface or atmosphere, which limits the length of falling cable to a few dozen miles. The rest of the cable would actually move away from Earth.
Re:There has to be a practical reason... (Score:2)
I've heard the numbers before, but I can't recall off the top of my head...
I know for certain that current "shipping costs" to get into space are roughly US$10K/lb. The space elevator should reduce that to something like US$200/lb. if I remember correctly (it may be lower).
Never forget the reliability factor. We think space shuttle flights are routine, but they're not very frequent, which means the low number of disasters is primarily due to the low number of flights. From what I've heard directly from NASA, if one shuttle were launched every day, we should expect to lose one every year, give or take a few months.
Re:Waste of Time? (Score:2)
I take pretty much the opposite position, since I've seen some of the numbers and caught a glimpse of how things are run. Unfortunately our governments don't like sharing information (cold war habits die hard, I guess) so frequently scientists from different countries are not allowed to collaborate on experiments. To me, if scientists from different nations can't work together, there is no real purpose in having an "international" space station.
As for propulsion, what type do you mean? A space elevator would lower the cost of getting into geosynchronous orbit tremendously. From there, it's much cheaper to go anywhere else. Just about all of the new propulsion schemes I've heard of either don't produce enough thrust (ion propulsion) or too much radiation (nuclear) for the first part of the trip.
Re:There has to be a practical reason... (Score:1)
DB
Re:Space Teathers and elevators (Score:2)
No amazon url due to patent madness. Choose any online source you want for more info...
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Re:What if you get stuck (Score:1)
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\ / in HTML and M$ proprietary formats.
X
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everest is ~5.5 miles high, not 2 (Score:1)
but I get your point, 31 miles is an awful tall building
Re:Always wondered... (Score:2)
right?
Re:Space travel isn't feasible (Score:1)
I don't think the idea was ever to launch them from the Earth's surface using nuclear engines. More like assemble them in orbit or on the moon and then fire them up.
Space Teathers and elevators (Score:3)
Re:J. Storrs-Hall's space ramp (Score:1)
10 g's accelerating you while you face forward is not so bad as 10 g's in a jet even. The latter forces blood into your feet, causing you to pass out. The former would just force blood to the back of your body. If sitting, this would simply result in blood flowing out of your legs and into your chest and head. Big deal.
On the other hand, at around 47g your eyes explode and you die.
Re:What if you get stuck (Score:1)
Oh, and go read the book. It's well worth it, and not just for the large divot they take out of the equator.
KdL
Re:There has to be a practical reason... (Score:2)
As I recall the electrical energy costs are around US$1/lb to GEO, and since the propulsion and guidance uses no physical contact with the elevator there is essentially no wear and tear. OTOH, there would be huge construction costs to write off, but it would still probably not cost more than, say US$10/lb assuming a large amount of traffic.
/Dervak
er??? (Score:1)
A building that's 31 miles high??!? Isn't Everest about 2 miles high? And isn't the Mariana Trench about 5 miles deep? And they say we'll have a man-made building finished "50 years away probably" that will be 31 friggin' miles high?
What kind of bud are these guys smoking?
Trains stop at a train station. Buses stop at a bus station.
Re:There has to be a practical reason... (Score:1)
Re:There has to be a practical reason... (Score:1)
Re:There has to be a practical reason... (Score:1)
Waste of Time? (Score:1)
I think any money spent on even planning it is a waste and may as well be put towards the above causes.. (Untill we have the resources if we ever do)
just my $AU 0.0375
For More Info (Score:3)
Re:Always wondered... (Score:2)
What if you get stuck (Score:3)
I doubt there's enough Mentos in the world to get ya out of that situation
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63,000 bugs in the code, 63,000 bugs,
ya get 1 whacked with a service pack,
Re:Silly question about vacuums (Score:2)
> space was a vacuum. If we put a platform in
> orbit that had an elevator going from earth to
> outside our gravity well wouldn't it serve as a
> tube to just suck our atmosphere out into space?
That is exactly like saying that if I drop a drinking straw into a glass of water, the water in the glass will spontaneously shoot out the top of the straw and empty the glass. Clearly that would never happen with a straw that was 50 cm long, why would it suddenly happen if the straw were 32000km long?
Re:J. Storrs-Hall's space ramp (Score:1)
It's a great idea. It works fine in test models. We could probably build it, especially with the recent developments in workable maglev. But without a nation that understands science, or space, or why it's important to go, it's not happening for decades. If ever.
The U.S. will never build a space-based civilization. We're too fat and self-absorbed. We don't understand math, we hate science, and we distrust brainiacs. We'll spend the next 50-100 years debating theology's place in government, and refighting the civil war in endless ways.(if you don't think Bush's election was a victory for the New Confederacy, think again.)
Less negaitively, I think that space may be eventually be colonized by smaller nations, who have less investment in history and more hope for change in the future. Look to them for interesting projects.
Re:er??? (Score:2)
Think guyed tower, not building. The problem is dealing with wind loading for the part of the tower that's in the atmosphere.
Space travel isn't feasible (Score:3)
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Chemical rockets.
Chemical fuels aren't powerful enough for useful space travel. Even with the best possible fuels, you
either need disposable stages or have tiny payloads for the size of the craft.
Heinlein pointed this out in the 1940s.
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Nuclear rockets.
Too messy. The NERVA program made real progress,
but open-cycle nuclear reactors spray radioactive waste. Closed-cycle ones are too heavy, and messy if they crash land. Orion, the A-bomb powered spacecraft, was even worse in that regard.
Still, if you launched from, say, halfway between Cape Horn and Antartica, where South Africa once tested an A-bomb without bothering anybody, it might work.
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Antimatter propulsion.
Dangerous, but feasible. Antimatter can be contained in electric and magnetic fields. Portable containers for antiprotons have been built. If anything goes wrong, all the energy comes out as gamma rays. Another one of those "the launch site had better be really remote" launch systems.
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Laser launch. A big laser on the ground
heats up water in the spacecraft to make steam.
May be feasible for mini-spacecraft.
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Antigravity.
We have no idea how to do this.
But it might not require new physics.
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Beanstalks, tethers, etc.
Requires really good materials in huge quantities, along with some other big-time means of space travel for
the construction.
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Winged launch. The Pegasus rocket was launched from a B-52, and souped-up fighters
have made it to the edge of space.
Helps the fuel problem a little, but not as much as is really needed.
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Cheap, dumb boosters. The original Von Braun plan: mass-produce lots of cheap disposable rockets,
build a big space station, and operate from there.
Boosters have been mass-produced as ICBMs,
but never got cheap enough.
And that's the way it is.Build it out of Buckytubes (Score:2)
On an interesting side note, Clarke had originally written about a space elevator connected to a tiny island, but I can't remember the book (it was before 3001). I do recall that the island was conveniently very similar to Sri Lanka (where Clarke lives) but moved south to make the physics work.
Re:Anchor it to an asteroid?!? (Score:2)
Re:There has to be a practical reason... (Score:1)
Re:There has to be a practical reason... (Score:1)
Re:There has to be a practical reason... (Score:1)
Anti-Gravity Research Confirmed
http://slashdot.org/science/00/03/28/0815202.shtm
NASA seeks to verify Gravity shield
http://slashdot.org/articles/98/12/11/1236240.sht
Practical Gravity Shielding for Spacecraft?
http://slashdot.org/articles/00/03/28/2154213.sht
Re:3001: Humungous Diamonds (Score:1)
Richy C.
Re:Too dangerous (Score:1)
Richy C.
Re:For More Info (Score:1)
The Cheshire Cat wrote:
The How Stuff Works link that Cheshire Cat provided is not that good -- it basically is a restatement of NASA's own page [nasa.gov] on their FD-02 Space Elevator concept, only with added ad banners. In addition, the How Stuff Works site attempted to set persistent cookies on my machine about 10 times before it gave up.
In short: visit NASA's page [nasa.gov] and avoid How Stuff Works.
Re:J. Storrs-Hall's space ramp (Score:1)
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Re:J. Storrs-Hall's space ramp (Score:1)
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Re:Silly question about vacuums (Score:1)
Why? Just because you have a tube running between the Earth and Moon (ignoring the problems with that, which are huge), you haven't repealed gravity -- which is what holds the air on Earth. The air in the tube's not going to decide to go somewhere else, just because you put a wall around it.
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Re:high shear stress (Score:1)
While there are aerodynamic forces on the cable, they're fairly small compared to the tensional forces, and can be managed by guy wires... just as with any tower.
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Re:high shear stress (Score:2)
You put the bottom end on the equator, and the center of mass in geosynchronous orbit; the counterweight is above GEO. Then the "beanstalk" is in pure tension, with no shear at all.
I think you're trying to put all the different parts into orbit, whereas only the GEO point is moving at orbital speed. Sure, the parts above and below that aren't (lower tries to fall down, upper tries to "fall" up) -- but they can't go anywhere because the structure holds them in a fixed relationship. In tension...
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Re:Space travel isn't feasible (Score:2)
There's nothing fundamental in the physics that prevents "space elevators;" it's just a materials problem. We'll get there soon enough...
(As for your "big-time means of space travel for the construction" comment: we need one asteroid, which could be brought back by a robotic mission, and one minimum-strength tether line in geosynchronous orbit. Unreel that line in both directions, grab the lower end, and use that line as the first strand of the elevator -- you can run all the remaining structure up from the bottom, increasing capacity as you go. If capturing the asteroid at the right moment makes you nervous, you can drag the counterweight mass up the elevator too -- it just takes a little bit longer, and uses some more electricity.)
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Re:What's the american degree for -1? (Score:2)
About the outer endpoint of the system: typical designs use a large mass (like a small asteroid) at the outer end of the cable. Since it's beyond geosynchronous orbit but still moving around Earth once every 24 hours, it's going too fast for its orbital altitude; it therefore tries to move away from earth, but is kept in place by the cable. The result: enough tension to hold the cable "up." You select the tension by choosing the mass and its location relative to GEO. (Alternatively, you can make the cable longer to achieve the same result; but cable's expensive, while asteroids are relatively common.)
To answer your question about connecting it to the ground: The proposals I've seen usually put a large "foundation" in the ground, and attach the bottom end of the cable to that. A rather similar thing gets done at the ends of a large suspension bridge: the cables at each end are pulling toward the center of the bridge, and must be anchored. I suppose an alternative would be to attach it to bedrock, but I think I'd rather engineer the attachment -- that way I would know exactly what it's capable of handling.
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Re:What's the american degree for -1? (Score:3)
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Reality and Bucky (Score:2)
http://www.space.com/businesstechnology/technol
The reality in the article is next June's space tether experiment in generating electricity (using the power directly for spacecraft propulsion):
http://www.space.com/sciencefiction/books/forwa
Of course the best known material to be strong enough for a space elevator turns out to be buckytubes...
John
Re:There has to be a practical reason... (Score:1)
Regardless, I think the real point is that unless we are moving a LOT more to space than we are today, then a space elevator is essentially non-useful.
Re:There has to be a practical reason... (Score:2)
Think of it this way: Which is cheaper: Riding an elevator to the top floor of a skyscraper or using a helicopter to do the same thing? A shuttle ride is around $22,000 per kilogram today. The estimates most people put on a space elevator is around a buck or two a kilogram.
Today, there probably isn't enough practical use for this to justify the expense. In the future, especially when we start mining the moon and/or asteroids, this will become a big issue.
Another point is that a space elevator can actually serve as the initial boost for interplanetary trips. The top end of the elevator is actually above geostationary orbit (the center of mass is at geostationary orbit - 35786 km) and as such when you figure the math using a conservative 36,000 km orbit, you get the fact that the top end is actually traveling well over 225 million kilometers in 24 hours or just under 9500 km/h (roughly 5900 miles/hour). This saves a LOT of fuel costs. You basically just wait until the right point and then "let go" and you're on your way to the moon, or mars, or....
Re:What would happen (Score:1)
Short version: cable wraps itself around the planet a couple times, with the parts that were higher up hitting faster. Of course you have the friction of reentry as it comes back in to take into account, so the thing is fairly nasty. You end up not wanting to be anywhere near the equator when it comes down.
Another interesting thing he brings up in a later book, Blue Mars, is a way to get around the tether point needing to be on the equator: Split the cable about 10,000 miles up, and have it tethered to 2 points eqiudistant from the equator. This opens up _lots_ of possibilities for where to put the thing, as opposed to being stuck right on the line.
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Your mouse has moved.
Windows NT needs to be restarted
for this change to take effect.
hmmm.... (Score:1)
Kudo's
To bad Space Elevators are the Super Dense Optical Storage Devices of Space Industry. A Red Herring.
suggested Space News Site's spaceflightnow [spaceflightnow.com]
SpaceDaily [spacedaily.com]
NasaWatch [nasawatch.com]
SpaceWeather [spaceweather.com]
Nasa [nasa.gov]
It's ashame that SpaceOnline [flatoday.com] bit the dust and was absorbed by space.com [space.com], along with SpaceViews [spaceviews.com]
If you want some real action become a Nasa click worker at http://clickworkers.arc.nasa.gov/top [nasa.gov]
Maybe Slashdot will even do a story on it...
I wait with herring baited breath
Re:Cool as this is, think about physics and politi (Score:1)
Kim Stanley Robinson demonstrates the destructive potential of this type of elevator excellently in his book Red Mars. In the story, someone blows the orbiting "counterweight" off the end of the cable. Without the large mass in geostationary orbit to keep the cable straight, it basically falls over, wrapping around the planet a couple times in the process and flattening everything in its path. And everything nearby, since by the time the upper half hits the ground, it's travelling many times the speed of sound, packing quite a shock wave in front of it.
Pretty scary stuff.
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Cost Effectiveness (Score:2)
Assuming this beast gets built, we have to keep in mind that at first (and, I think, for a very long time) there will only be one of these things.
Its cost effectiveness (and it's appropriateness for use by individual private passengers) must take into account the cost of transporting the people and cargo across land to the site of the tether.
I have no idea how to crunch these kinds of numbers. Has anyone else done so?
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Re:Silly question about vacuums (Score:1)
Re:Changing earth orbit (Score:1)
-- ShadyG
Tensile Strength (Score:1)
-- ShadyG
Re:Megascale Engineering (Score:1)
Re:er??? (Score:1)
Re:er??? (Score:1)
Re:There has to be a practical reason... (Score:1)
It's (theoretically) much, much less expensive to launch from space than it is to launch from the planet's surface. It's possible that something like this could make the use of local space cost-effective.
Holidays on the moon, somewhere to bury nuclear waste, strip mining and no complaints from the neighbours. Heavy industry could move up there and not worry about polluting the atmosphere - there isn't much of one anyway!
Makes you think doesn't it?
Re:Silly question about vacuums (Score:2)
but, take the thought experiment to the extreme, if the tube was long enough and extended far enough into space, and you could initially fill it with air, would it not act as a siphon? But, in regards to the initial question, the air in the tube doesnt know, and isnt acted upon by any additional forces, then the air right next to it on the outside of the tube.
Re:Silly question about vacuums (Score:2)
actually, after thinking it through, it wouldnt end up like a siphon, the air inside the tube at the far end would either escape, or get pulled down, until the conditions in the tube matched the outside of the tube, like a big barameter.
Changing earth orbit (Score:2)
Cool as this is, think about physics and politics (Score:3)
Also, the thought of having one doorway to outer space, under the control of some political force or another, does not strike me as safe. Considering the kinds of mass destruction that can be wreaked on the rest of the work from orbital heights means that this would not only be the space elevator, it would also be a major weapon. Lets face it, once something is in orbit, landing it in a particular spot is not that difficult. For those who do not believe, go get a copy of Navigation for Space Flight, by Prentiss Hall, I think (it's been a while). At the kind of energy levels we are talking about here, you don't have to be precise.
Besides, I want my OWN fricking orbital shuttle. I've got places to go besides Clarke orbit.
Re:What's the american degree for -1? (Score:2)
Megascale Engineering (Score:5)
If you are found of Dyson spheres, beanstalks, spacehooks, terraforming and other stellar husbandry, check out the following site, full or ressources on these topics:
Megascale Engineering [aleph.se]
There has to be a practical reason... (Score:3)
And this wouldn't really be a step in the right direction. Sure, research into new materials/engineering techniques would be fruitful, but what is this really?
An elevator to nowhere. Imagine how silly it'd look. :-)
Re:Hope no one here will be next NASA admin (Score:2)
The third one? That'd be the one that proves reaction rockets are impossible, right?
"As a method of sending a missile to the higher, and even to the highest parts of the earth's atmospheric envelope, Professor Goddard's rocket is a practicable and therefore promising device. It is when one considers the multiple-charge rocket as a traveler to the moon that one begins to doubt ... for after the rocket quits our air and really starts on its journey, its flight would be neither accelerated nor maintained by the explosion of the charges it then might have left.
"Professor Goddard, with his "chair" in Clark College and countenancing of the Smithsonian Institution, does not know the relation of action to reaction, and of the need to have something better than a vacuum against which to react ... Of course he only seems to lack the knowledge ladled out daily in high schools."
3001: Humungous Diamonds (Score:2)
All we need to do is find a bloody big diamond, or gain control of matter at the molecular level.
Or Jupiter can blow up. That would work as well...
Re:Always wondered... (Score:2)
Incidentally, the title of the article, "Next stop: low Earth orbit" is misleading: the only point in the tower where you can drop off and be in orbit with a little push is at GEO.
About Practical Reasons... (Score:2)