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Space Elevators: Low Cost Ticket to GEO?
Crocuta writes "The current issue of Science
News features a cover story
that discusses the current developments in space elevator technology. NASA has been
working on such devices for many years, but private companies such as Highlift Systems are now jumping on the space
elevator bandwagon, no doubt seeing the huge potential profit in a low cost per pound
delivery system. PhysicsWeb has a somewhat
older, but much more technical article
on the formation and structure of the carbon nanotubes that form the basis of the proposed
tether cables. With a development like this, we could shoot entire boy bands into space and make
the world a better place."
We have enough trouble getting stuck on elevators between floors in 5 story buildings. Could you imagine getting stuck half-way to the moon? They better be sure to put one of those bright red emergency phones on this bad boy.
Those of us already in orbit can't wait for the space elevator to be complete. Finally, we can get some cable TV.
With an object that goes through t the ionosphere you would get a constant stream of free electrons surging through the damn thing. Throw a power station at the base and BOOM. Free electricity. The only question I have is if we pull down electrons in the upper atmosphere would there be an impact?
-=[ Who Is John Galt? ]=-
Arthur C. Clarke popularized the Space Elevator and once said "The space elevator will be built about fifty years after everyone stops laughing".
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http://science.nasa.gov/headlines/y2000/ast07se
My father is a blogger.
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"A microprocessor... is a terrible thing to waste." --
GeneralEmergency
As fascinating as it sounds, unfortunately, Congress will never fund such an endeavor -- as far as they concerned, space is a useless void that we now have no reason to explore after the death of the USSR.
The idea might be feasible -- I prefer the idea of a giant cannon/mass driver/gauss gun to shoot us into space myself -- but the idea of a 100,000km tube supporting an elevator is too farfetched to ever get funding, especially with increasingly conservative US administrations that would rather spend money launching rockets not into space, but into third-world cities, as well as European powers that have their own budget problems due to their social welfare systems that prefer to spend money on Earth and not in space.
The problem with something this tall is that it will inevitably be destroyed, and we will be scattered throughout the earth and forced to speak different languages.
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Here are some more links to info on our very own Slashdot:
Here
Here..
Here..
and Here
Here's a nice sized (15MB) report done by NASA. They talk about all sorts of problems that need to be worked out to make get this project off the ground http://www.niac.usra.edu/files/studies/final_repor t/pdf/472Edwards.pdf
free ipod? yeah.
You build it in the middle of the ocean on an old oil platform. You create a military-like death zone around the platform, say going out 50 miles in all directions. It might be hard to protect something like this built in a city, but in the vast expanses of the ocean, not a problem.
Casca
The minute I saw it on slashdot, just like the last time, I knew people would go into the "this is just impossible" mode without at least giving it a shot.
Ok, I'll bite. READ THIS (warning, it's a pdf file), and once you do, say it again. I'm not saying this paper is wrong, but it's enough information to realize that there's no one thing preventing it form happening. Not even money, as it would all cost about the same as the International Space Station. The one thing that doesn't exist as of yet is the nanotube wire, which feasbility is clearly only a matter of time. So if the existance of the Space Elevator depends on the existance of a 90,000 Km long nanotube wire (the fabric industry is used to threads this long, again, read the paper), then there's no doubt that it will become a reality.
The space elevator is doing for me what the apollo program did for my parent's genration: It's giving me an overdose of inspiration.
There are two kinds of people in the world: Those with good memory.
top floor: shoes, ladies ligerie, space. please mind the gap.
Cars will be drawn to the top of the elevator by a team of trained mules, hitched to a rope of a length roughly 1.8 times the circumference of the Earth. We anticipate only minor difficulties obtaining a right-of-way through most nations (with the possible exception of Sweden, because they're lame).
The mules will be fed and cared for by dedicated and highly trained staffpersons. At the end of their useful lifespan, most retired mules will be adopted by loving families everywhere. Unclaimed mules will be shot, as will be unclaimed members of loving families. Irresponsible and gratuitously hostile critics, who clearly do not have the best interests of humanity in mind, will be shot also.
On special occasions and international holidays, children of all races, creeds, colors, and nationalities, clothed in their quaint and colorful native garb, will be invited to throw superballs and apples from the top of the elevator. They will be charged only a nominal fee for this unique privilege. Highly sophisticated surveillance technology will enable all the world to enjoy the festivities!
We are now accepting investments in this historic, one-of-a-kind investment opportunity, not to be missed by the progressive and forward-thinking investors of our great nation. We anticipate incalculable earnings; we also anticipate neglecting to calculate them. Please give us all of your money right now and I promise you'll not regret having been so easily gulled.
"Offtopic, Inflammatory, Inappropriate, Illegal, or Offensive" -- hey, that's me!
Sounds like more of a Shelbyville idea...
"I may be quite wrong." - Socrates
Couple of points :
There are obviously enormous difficulties with building this cable, with having it survive lightning strikes, deliberate damage ( could a single guided rocket with an armor piercing molten jet warhead destroy this wire in one hit? If that happened, wouldn't the $10,000 missile have caused 50 billion worth of damage or more...everyone knows that a project like this is going to cost 10 times the current estimate), the mechanical wear as the spacecraft slowly claw there way up...
A far simpler and cheaper solution is a massive ground based laser array. (which incidentally is how they are proposing to power this thing...why not skip the cable and build a much bigger laser). The beam would vaporize propellant attached to the bottom of the spacecraft, eliminating perhaps 90% of the danger of rocket travel (the rocket blowing up has always been the biggest risk...if it uses a nonvolatile, inert propellant) and reducing the cost to a tiny fraction of current expenses.
Since the laser system would be a large array, it would not have to be built to nearly the quality standards that a manned spacecraft has to be constructed to since if one of the lasers burns out, blows up, ect the rest of the system picks up the slack.
You don't need to tether the end, you can still get some very healthy benefits with a partial elevator. Deals with a lot of the security issues too. Cargo craft only need to fly to the low end and ride the rotation to the top where they can slingshot off. Using the Earth's magnetic field and solar power means it's self-stabilising too. More detail and better writing at; Free David Brin Short Story
Ok, as much as we all laugh at Lance, or whatever his name is, from N'Sync trying to go into space, I think it was moronic of everyone involved not to make sure this happened, that he got up there and back safely, and had one hell of a good time.
The entire space program has been gradually fading from world view, and particularly from the Western world. Yes, there are programs still going on at NASA and ESA and even in China, but it's nowhere near what was hoped for in the 1960s and 70s. Putting a high profile celebrity into space would bring a lot of attention back to the space program. Would it be fleeting? Of course. That's what media attention is nowadays. But it would probably enspire a lot young kids to go to space, just as the early US and Soviet astro/cosmonauts did nearly half a century ago.
All true, but you missed two points:
BZZT!!! No, you're forgetting that the planet has its own velocity, which a spacecraft can steal. When a spacecraft slinshots around a planet, its velocity on the way out is the same as its velocity on the way in, but this the the velocity RELATIVE TO THE PLANET. If the spacecraft approaches the planet head-on, and does a 180 degree slingshot around the planet, then (ideally) its final velocity RELATIVE TO THE SUN is equivalent to its initial velocity plus two times the planet's orbital velocity. Energy is conserved, because the energy gained by the spacecraft is stolen from the planet.
That's "Mr. Soulless Automaton" to you, Bub.
Think of the space elevator structure as a 100,000-km-long highway that will require ongoing maintenance and repair," says Smitherman.
How unrealistic can an analogy be? If a crack forms in some remote stretch of interstate, there's no danger of the rest of the interstate system suddenly ripping away and falling into space. Repairs would have to happen instantaneously without ever breaking an almost unimaginable ribbon tension. And this wouldn't be a very rare occurrence, either, as the ribbon would present a surface area of five to eleven million square meters on each side (5 to 11.5 cm wide, 10^8 meters long). And remember that it's on the equator, which every piece of orbiting debris crosses twice during each orbit.
And the only mentioned solution for lightning strikes (one of which could be fatal to the ribbon) seems almost totally unworkable, and doesn't take into account that a 100,000-kilometer-high conductive tower would generate its own lightning. Remember the ill-fated (but educational) Space Tether Experiment? And the tether was only a mile long. A space elevator's ribbon would intersect a huge chord of Earth's magnetic field, including both Van Allen Belts. Seems to me that, even if the ribbon didn't immediately blow like a giant flash-bulb filament, you still couldn't get within a hundred yards of the base due to the continuous electrical discharge.
Don't get me wrong--I've dreamed about space elevators since I was a kid reading about Clarke's hyperfilaments, but the more I think about it, the more unworkable it seems.
Will the wire generate power?
Yes, but only in the milliwatts.
Tim
Omnia vestra castrorum habetur nobis.
Nothing can be protected 100% completely from attack by terrorists (or anyone for that matter). There is always a risk that if someone really wants to see something destroyed, they can do it.
That said, however, putting a ribbon to space out in the middle of the ocean, away from any shipping lanes, international flight paths, or human activity at all is a good start at protection. It's HARD to get to a location that far removed from everything without anyone noticing (especially if that location is under constant watch and guard.
Additionally, this operation, while not devoid of human workers, won't have so many people laboring at the anchor-station or on the cable to make a terrorist attack really that fruitful. There just isn't that much casualty potential (although the capital losses could be considerable).
But capital is just money. And the neat thing about money is if you spend it on projects which create wealth, you're not really losing it. If the cable can operate for a few years, it will have paid for itself, anyway, and very likely several additional cables will be built to expand capacity. These cables will most likely expand radially from earth all around the equator, under the control of diverse groups of people. We already know that humans want to get out into space and explore it, even at considerable expense. The proposed budget for the cable is not chump change, but nor is it unreasonable when compared to other space projects. America alone has spent considerably more on the Space Shuttle program over the past 25 years, and for that money, we'd be able to lift up as much material (measured by tonnage) in 2-3 years as we have in all the Shuttle missions combined. So the real risk of huge financial loss is if a terrorist destroys the cable in that initial timeframe. Additionally, since most of the cost is in the research, design and development, rather than the construction and deployment, another cable could be built if the first one is destroyed (admittedly, if the first one is destroyed very quickly, there will be a huge political barrier to overcome before a second cable could be deployed).
Also, since the thing is so cheap to operate, many more nations, companies, and individuals will be able to afford to undertake space-based projects.
The thing is, if the whole world is given access to space, There won't be that much motivation to destroy the means to that access. If one country or company jealously hordes the cable and doesn't lease out usage to everyone else, that country or company will:
1. Risk considerable reprisal, both in the form of economic sanctions by the rest of the world, possible military threats, and very likely terrorist threats
2: Miss out on a fantastic opportunity to enhance the economy of the entire planet, and line its own pockets considerably in the process.
Therefore, it will be in the interest of whoever builds such a machine to let the rest of the world use it as well, including the deployment of components for the construction of additional cables.
Instead of spending billions to perfect a safe, efficient delivery method why not just unravel the world's largest rubber band ball; tie them all together; and shoot the boy bands (one at a time for greater distance) into space?
One thing I never see mentioned by all these proponents of nanotubes as a structural material is that extrapolating the strength of nano-scale covalent bonds to macroscopic dimensions is overly optimistic. "Calculations suggest... based on flexibility... 100x as strong as steel" sure. There are all sorts of materials, if you remove all the defects on an atomic scale, that are super strong. But saying that it is inevitable that we can scale up something from 1 micrometer to 100,000 kilometers is a bit of a stretch. If you made the cable out of solid flawless diamond, it would be stronger than out of nanotubes, and we can already make bigger diamonds than we can make nanotubes. I think a space elevator would be great, but don't hold your breath. There are a lot of details to be worked out in the materials science area before it is really a possibility. But nanotubes do hold promise, just not as much as everyone here seems to think.
So yes, there are many challenges to overcome, but they all, fortunately, seem surmountable.
How could it be defended from someone who doesn't care whether he lives or dies as long as the target is destroyed?
How about removing the single point of failure?
What if the cable split into a few hundred strands, and was anchored in such a way that it covered a good 1KM radius on the ground, with lots of room between the strands? Perhaps a fully-loaded 747 could take out a 747-wide swath of the cable ends, but it couldn't hit enough of them to threaten the overall integrity of the elevator.
Basically, it's just an engineering problem. A single mass of cable would be pretty difficult to destroy already, and strategies like I've just described could make it even more difficult.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
Microsoft could build this thing *OUT OF* cash!
So of course, this being Slashdot, I get flamed and modded down by geniuses who don't know a fucking winking smiley when they see one.
Sigh... well, not like it matters. Excellent minus 2 is still Excellent, in all probability. And if not, well, it still doesn't matter.
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