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Space Elevator Going Up
Adlopa writes "The
Guardian newspaper reports on scientists' efforts to realise the space elevator, as first described by Arthur C Clarke in his 1979 novel 'Fountains of Paradise'. Advances in materials science mean that 'a cable reaching up as far as 100,000km from the surface of the Earth' is no longer an impossibility and 70 scientists and engineers are discussing the idea at a conference in Santa Fe today."
will it have a 13th floor?
-knowles
Any excuse to hang out in Santa Fe is a good one.
At about a third of the way along the cable - 36,000km from Earth - objects take a year to complete a full orbit.
Uh oh...
~ Give me 101 plastic soldiers, and I will conquer the world.
From the story:
----
A space elevator would make rockets redundant by granting cheaper access to space. At about a third of the way along the cable - 36,000km from Earth - objects take a year to complete a full orbit. If the cable's centre of gravity remained at this height, the cable would remain vertical, as satellites placed at this height are geostationary, effectively hovering over the same spot on the ground.
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Actually, at 36,000 km from earth, objects take a day, not a year to complete a full orbit. The moon takes about 28 days to complete an orbit, (one lunar cycle) and any object far enough out from the earth to require a year in order to complete an orbit would passed the instability limit, where it would be captured away by the sun's gravity, and would no longer orbit earth.
My rights don't need management.
http://www.spaceelevator.com/ About the only place I could find with all the information piled into one spot.
Shredded plane. (strong cable - duh)
And the lowest note ever twanged.
Imagine the fact that the tip would accelerate as it fell...most of it would end up burning up in the atmosphere. Also imagine how little of the earth's land area lies along the equator. Not much. It might cause some localized devastation, but it's not a world-breaker.
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Why would it have to be at the poles? I can't see any reason whatsoever for that restriction.
Imagine the fact that the tip would accelerate as it fell...most of it would end up burning up in the atmosphere.
That's true, the risk of the thing falling down and crushing people is almost zero. But there is another problem: if it burns, will the resulting particles be hazardous for us to inhale? There's research going on about that.
But But But
When a cable under stress breaks it can cut right thought metal...
When this long whip breaks, it will slice right thought the earth!!
Quote from the article:
"Until some of the basic science concerning how to connect nanotubes together and transfer load between them in a composite is understood it will remain elusive, but a lot of progress is being made."
Basically, the state of the art with carbon nanotubes is that you can build them a few centimeters long, of almost/just about the right strength (72 Gpa); but nobody has made or can make a rope even 1 foot long with the right strength (ideally 130 GPa including a 50% safety factor).
State of the art carbon nanotube ropes are down under 3GPa (less than Kevlar strength). To oversimplify the problem nanotubes are very slippery and hard to join with any strength. Splicing rope out of threads traditionally loses 20% of the strength, but nanotubes are too slippery, and not strong enough anyway for that right now.
Still, enormous progress has been made; and it looks surprisingly promising; but it's impossible right now.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"Thats the longest extension on a CAT-5 I've ever heard of, I'd go with wireless instead.
You'd also have God's wrath to deal with when he trips over it when going to the fridge for a midnight snack.
If you outlaw the law, only criminals will have laws
I don't mean to sound too condescending, but really, the centrifugal force of earth's rotation makes that impossible. I would have been humoured if you would have stated imagine a 100,000 km cable being hurtled at the moon when I move there. For it to fall to earth would mean the earth would stop spinning...highly unlikely given what we know.
You might be able to argue that inertia from the atmosphere would allow it to operate like a whip, but even that is farfetched. I doubt they would implement such a system without properly addressing such an issue.
Be more afraid of Near Earth Objects. Of course those things fall from roughly 4.7E17 km. Why the hell don't people imagine that?
One unlikely problem could be capturing the public's imagination. "When we actually start launching this it's going to be kind of boring," Dr Edwards said. "There's no smoke, there's no pillars of fire and there's no loud rumbling noises. There's just this thing that slowly ascends the ribbon into space."
This problem would be neatly solved once the initial expense of the elevator was recouped. At this point it would be much cheaper to send objects into orbit, including people... ride up the chain, get on a space suit, get out on your own nanotube cable and float around 36,000 km above the earth without ever needing to learn how to help fly a space shuttle.
I foresee an enormous tourist interest, to the point that someday several elevators will be sent up exclusively for tourists to use.
Nasa played around with dragging wires through the atmosphere to generate static electricity.
This thing will could possibly generate HUGE amounts of SE as the atmosphere whizzes past it 24/7. Are there plans to capture and use this electricity or what??
calculating orbits by hand (this was before the advent of the PC, remember), for example. Much of our scientific and engineering achievement today was first written about by Sci Fi authors, including personal computers, world wide networks, men traveling in outerspace, satellites, genetic engineering, waterbeds and much more. I personally hope we continue building what Sci Fi writers write about. Idealism and dreams lead to greatness. Pragmatism and "being realistic" lead to boredom and stagnation.
In my universe I'm perfectly normal, it's not my fault you don't live in my universe.
Fuck Iraq and let's cough up roughly 12 space elevators instead.
Hate me!
I swear to god, if my eyes roll any harder, they're going to fall out of my head.
It's not like we're talking about a high tension cable here. The cable's structure will be balanced by gravity -- the center of gravity will rest at the geosynchronous point, meaning that the bottom half will be falling toward Earth while the top half will be moving away at an equal rate. (Disclaimer: my degree is in English and I'm relying on this thing called "high school physics class"...)
Really, it depends on where the cable snapped and what the nature of the accident was...
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Imagine a 100,000 km cable falling to earth.. I wouldn't want to be under it.
The cable is actually pulling up. Catastrophic failure at any point along the cable results in it leaving earth.
Basically, you put the center of gravity of the cable right at geosynchronous orbit (ideally you want it to be a little higher than that)
If it's at geo orbit, then the cable stays still even if you cut it off. A hurricane would push the cable sideways, tidal gravity is enough to keep the cable taut by itself. It's a non-stable equilibrium however; eventually the cable will drift enough to escape earth gravity. Unless it hits a mountain first. But even then, EVERYONE is under it. It'll wrap around the earth at least once before it's done falling...
I am disrespectful to dirt! Can you see that I am serious?!
New continents were found, the sound barrier was broken and even space flight was developed at the cost of human life. Yet, it was worth it.
As a species we have become too concerned about safety. We are afraid to such extent that testing new discoveries (medicinal, chemical and physical) are becoming so burdened by the hysterical safeguards, governmental red tape and the associated costs that nothing ever gets done. To my mind, this development threatens the very progess of our species.
BOO! TERRO
Pretend that I posted a lame joke about listening to elevator music for a very long time. Then mod me up as "Funny". Half of the so-called "Funny" posts aren't, so this one will fit in nicely.
It _is_ pretty scary to think about a paper thin ribbon of material falling on your head. It would probably get in your hair and necessitate a shower and a vigorous shampooing.
A space elevator would make rockets redundant by granting cheaper access to space. At about a third of the way along the cable - 36,000km from Earth - objects take a year to complete a full orbit. If the cable's centre of gravity remained at this height, the cable would remain vertical, as satellites placed at this height are geostationary, effectively hovering over the same spot on the ground.
Objects take one DAY to complete a orbit at 36,000 km... and if that orbit is in the same direction as the earth turns, then you can orbit continuously over a spot on the equator. There's actually a minor perturbation, but those forces are minor compared to the other forces a space elevator would have to deal with...
BTW, a nice recent sci-fi novel on the subject of space elevators is _Rainbow_Mars_ by Larry Niven, of _Ringworld_ fame.
I am disrespectful to dirt! Can you see that I am serious?!
From the article: "When we actually start launching this it's going to be kind of boring," Dr Edwards said.
After watching rockets (and shuttles) explode into spectacular fireballs, boring is just fine with me. Considering the majority of mass on any rocket is used to just get it to a level of orbit, this could be a nice way for us to start working toward the moon (and eventually beyond) again.
The really exciting will no longer be GETTING into orbit, but rather what we can do once we get there.
Tequila: It's not just for breakfast anymore!
It is better to remain silent and be thought a fool than to post and remove all doubt.
Guestion for you - what do YOU think would hold this thing up? Maybe you expect a bunch of Indian Fakirs to be sitting around the base blowing on flutes? (reference to Indian Rope Trick for those who were wondering...)
To answer my own question, the fact that one end of the cable is moving faster than the other end makes the part that is moving want to fly off in a straight line - but the tensile strength of the cable keeps the two hooked together. If the cable were at either of the poles, there would be a bunch less difference in speed between the two ends - and the system would be more UNSTABLE.
Acts of massive stupidity are almost never covered by warranty. --me.
...estimates it would take about $7bn (4.4bn) to turn the concept into reality...
So how exactly do you come up with a budget for a project that calls for an unknown (but massive) amount of nonexistanium, delivered to orbit no less?
But there is another problem: if it burns, will the resulting particles be hazardous for us to inhale?
Carbon nanotubes are primarily, well, carbon. Burning up would create the same stuff that charcoal makes, CO2. Potentially less toxic than second hand cigarette smoke. There may be some other chemicals in there, but the whole idea is to make the tube out of a single material, the nanotubes, to make it strong. So, yes, research is good, but toxicity is probably not the biggest issue.
Tequila: It's not just for breakfast anymore!
God Damnit... because of people like you Clarke once said "the elevator will be built 50 years after people stop laughing".
Would you please document yourself, make the appropriate research, concentrate for 2 seconds on the topic at hand before you open your hole and spill out the first fearful thought that comes to your mind?
- It would be built in the middle of the ocean on a floating platform
- If it broke, most of the 100,000Km would NOT fall to earth (junior high physics can tell you that), and most of the piece that would, would burn in reentry
- What remains would be much more harmless than your poisonous, unscientific whining.
You're like those people that hear the word "nuclear" and immediately thing BAD BAD BAD
There are two kinds of people in the world: Those with good memory.
From the article.... "The biggest technical obstacle is finding a material strong but light enough to make the cable; this is where the carbon nanotubes come in. These are microscopically thin tubes of carbon that are as strong as diamonds but flexible enough to turn into fibre. In theory, a nanotube ribbon about one metre wide and as thin as paper could support a space elevator."
I know the fiber is as strong as diamonds, and I understand that along it's 100,000 km length it's flexible enough to dodge objects.
But how will they protect it from, well, planes at altitudes below 100,000 feet?
Sigh.
Who modded THAT insightfull?
"Imagine an accident. I wouldn't want it to happen to me!" Is not insightfull.
We get these inane comments with every article about transport.
Electric cars: Imagine getting electrocuted.
Supersonic planes: Imagine a supersonic collision with a building.
Space elevator: Imagine it falling on you.
Ship: Imagine it sinks.
Train: Imagine it derails.
Etc, etc, etc.
We don't need to have those modded up! They're not saying anything original.
You can't take the sky from me...
a) Carbon nanotubes are strong but very, very light. They have a high surface area per unit mass. In the lower atmosphere, the cable would float to earth like a piece of fishing twine; in the higher atmosphere it would just burn up.
b) Not really. Airborne traffic is smart enough to deal with comms towers, skyscrapers and hurricanes. This thing does not move - all you need to do is fly around it.
c) Yes it does. In order to advance space traffic, we need to get to geosynchronous and LEO MUCH cheaper, allowing us to loft the larger masses necessary for more ambitious space missions. Getting big tonnages out of Earth's gravity well cheaper and more reliably than is currently possible would be a BIG win for space travel.
If you read the article, they are looking at the Pacific ocean as the base of the ribbon. If there was a real problem, and they needed it, it would be possible to cut the ribbon on the earth side, and this would force the cable UP instead of down. Not necessarily the best thing to happen, but it could burn up (carbon) in the atmosphere on the way back.
This stuff is pretty light, and they are looking at a RIBBON, not a cable. So the air resistance would prevent a 100 ft piece (for example) from accellerating to a speed that will cause any major damage. At least that is how I understand it after reading the article.
Same reason if you throw a sheet of paper off a tall building, no one is hurt. You throw a marble instead, and you can split a skull.
Tequila: It's not just for breakfast anymore!
That's in Science vol. 151(3711), p. 682 (1966).
Interestingly, Clarke envisioned the thread leading up (or down) the skytower to be nanodiamond, while these days nanotubes are all the range. The difference in the materials is that in diamond carbon atoms have four neighbours but in tubes they have only three, as in graphite, yet at about the same formation energy. That makes their chemical bonds actually stronger than in diamond and gives nanotubes their extraordinary tensile strength at low mass - perfect for engineering a space elevator.
The atmosphere (and the earths magnetic thing which induced the current in shuttle tethers) wont whizz past it, because the cable will not be moving relative to the earths surface. Charge from the atmosphere using the cable as a conduit is all covered in the space elevator faq's on numerous sites.
From what I've head, a space elevator is a bad idea in the sense that the atmosphere has a singificant EMF gradient between the surface of the earth and far up in the atmomsphere. Completion of such a device would case the world's largest lightning bolt ever. You'd be basically creating the largest "short" ever. :P
But how will they protect it from, well, planes at altitudes below 100,000 feet?
3 words: Restricted air space.
You can't take the sky from me...
According to A. Clarke himself the space elevator was invented by Jurij Artsutanov from St. Petersburg.
(3001, The final Odyssey, under sources)
Warning: This sig contains a small bug. ==> *
...about the space elevator is when the kid who launched his satellite just before you mashes every button before getting off.
Think about it. If it breaks at the centre of gravity, you're left with the bits being pulled down ONLY, and nothing to tension the cable from above. The outer part of the cable will indeed fly off into space, but the rest will still present a problem. Similar considerations will apply if the cable breaks somewhere else: the bit on the earth side will no longer be pulled away from the earth strongly enough.
John_Chalisque
The cable is only epoxied together, so anything past 100 km or so above the earth would fall apart into fibers during reentry (you'd probably blow it up into sections to help it melt correctly). Nobody knows what effect breathing these fibers in would have.
Incidentally everyone envisages the cable as being made of metal- it actually would weigh on order 1kg per kilometer, so it's not going to hurt you (although I wouldn't want to motorcycle fast at a section for obvious reasons.)
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"I can only shudder when I think about the new pick-up lines that arise once it is complete.
;)
"Hey Sweetie, wanna see my Space Elevator"
or
"Guess what is 3 feet long and DOES NOT reach into space"
and
"Let's play Space-elevator; I've got the cable, and you're gonna be the counterweight"
+++ MELON MELON MELON +++ Out of Cheese Error +++ redo from start +++
smooth, I love how you stuck that in there. Invented by Heinlein in '30's IIRC, He was trying to design a better hospital bed. I don't believe he ever actually built one, though.
Actually the centrifugal force is -exactly- what you want. The object is accelerated by the taut cable as it climbs it, so that when it reaches geostationary orbit it is travelling at the appropriate velocity. Remember that escaping the Earth's gravity well is about velocity, not just plain altitude.
9/11, 3-4 stolen lear jets evading 1-2 F-16s, ground hugging L-39s, heat seaking shoulder mounted SAMs aimed at elevators climbing the cable, Sharks with friggin laser beams (mounted in van filled with salt water) ... ?
"3rd floor; stereos, TVs, radios..."
"203rd floor; binoculars, range finders..."
"56,304th floor: parachutes, hang gliders..."
"124,202nd floor; helium baloons, oxygen tanks..."
"973,404th floor; motion sickness pills, glare filters..."
You're number four I disagree with. There's more than just the line itself. I'm sure the base would be fairly easy to spot and in a well-known location. After all this would be a major supply line into space.
Why are you speculating that anything would have to mass the same as the earth? The Earth orbits the sun, but doesn't mass the same as the sun!
The physics are simple: you just have a cord that stretches out beyond geostationary orbit. At geostationary, the cord's mass is in a precise orbit (zero pull towards or away from Earth); beyond that, the cord's inertia pulls it away from Earth. So you don't even need a lead weight at the end -- all you need is enough cord. As a bonus, anything that gets pulled past the geosync point will be accellerated away from Earth; so you can use it as a cosmic slingshot.
Hoist a chickenfarm to the end of the tether, and you can throw eggs at Mars!
-Billy
Read it again, I am sure you will eventually get the funny.
Oh hell, I will help you:
At about a third of the way along the cable - 36,000km from Earth - objects take a year to complete a full orbit.
You are right, "it takes one day to complete a full orbit at 36000km", BUT THAT IS NOT WHAT THEY SAID!
Acts of massive stupidity are almost never covered by warranty. --me.
Carbon nanotubes are primarily, well, carbon. ... Potentially less toxic than second hand cigarette smoke.
What if it was made of marijuna nanotubes? Imagine a fatty from here to the moon? That would be some serious toking.
With condolences to Tommy Chong.
When information is power, privacy is freedom.
The estimate of 7 billions $ seems very, very, underestimated.
And I suppose all known NASA locations are not consider as potential site to build this escalator, most of them are much more to near regions where tropical storms are likely to happen. Because, what would happen to a nice 1 meter large, paper thin, 100 000 km long light weight ribbon under a tropical storm? For sure, it will be hard to align the laser beam on the vehicles.
Achille Talon
Hop!
Static electricity, by definition, doesn't move, so it's useless.
:D
Not true. You can harness it's awesome powers to make inflated balloons stick to the ceiling, after you rub them on your head. You can generate it by running your feet on the carpet in the winter, and touching your brother, making him leap 3 feet. It makes pulling clothes out of the dryer much easier: Just grab any one piece, and the rest stick to it.
Ok, not the most useful applications, but still fun.
Tequila: It's not just for breakfast anymore!
http://isr.us/spaceelevatorconference/
Dragons.
I read a documentary about this once. Different colored (gold, bronze, brown, blue, green) dragons shall fly around protecting us from the falling thread. They fly fast, they fly between, and the burn the elevator as it falls.
Pilots of varying genders and ages ride the dragons, communicating with them telepathically.
The close telepathic connections, the sensual relationships between dragon and human are corrupting of course to the rest of society, and eventually all become obsessed with the dragon writers of porn.
Its not Static electricty. If you run a wire loop threw a magnectic field you will generate current and a drag force, if you push current you will generate a force. This is how electric moters and generators work. So In theory if you had a big wire loop in space you could run a current threw it and use that force to speed up your orbit, which would push to you a higher orbit.
They have had tecnical problems when they have tried it but they physics is all undergrad E&M.
Erlang Developer and podcaster
Actually, yes, we are. That's why advances in materials science were necessary before they could even think about building this thing. I quote from the article:
The cable's structure will be balanced by gravity -- the center of gravity will rest at the geosynchronous point, meaning that the bottom half will be falling toward Earth while the top half will be moving away at an equal rate.
Being "balanced by gravity" means there's a huge amount of tension here. In fact, that basically says that the top half (by mass - by distance probably a very small proportion of the thing) holds up everything below the center of mass at the geosync point. (Or from the other perspective: the bottom half holds down the top half, which would fly off into space otherwise.) It does that with tension in the cable, and we're talking about a lot of tension in the cable.
Let's put concrete numbers on it: carbon nanotubes are pretty light, but we're still talking about 35,785 kilometers in the bottom half (by mass) of the elevator - that's geosynchronous orbit around the earth. Say the elevator is 1 kg / m (very conservative, I think), which we'll call lamba (normal for linear density). Now gravity changes along the length of the cable (that's sort of the point), so we need an integral to calculate the force of gravity pulling the thing down:
F = \int GM dm/r^2 = \int GM \lambda dr / r^2
(where dm = \lamba dr). From my Physics I book, r_e (the mean radius of the Earth, which is a bit higher than sea level but not too bad) is 6.37 * 10^6 m. M (the mass of the earth) is 5.98 * 10^24 kg. And G is 6.67 * 10^-11 N*m^2 / kg^2. So the integral becomes:
F = \int_{6.37 * 10^6 m}^{6.37 * 10^6 m + 3.58 * 10^7 m} (6.67 * 10^-11 N*m^2/kg^2) (5.98 * 10^24 kg) (1 kg / m) dr / r^2 = 5.3 * 10^7 N = 53 MN (mega-Newtons)
...which I think is the require tension right above that point. I can't think off-hand exactly how geosync works, but essentially the stuff above that is being sped up and the stuff below (and the Earth itself, though not significantly) is being slowed down by that tension.
Disclaimer: I'm an undergrad physics student with a headache. I very well may have made a mistake above, but I guarantee it's closer than the parent post.
Mod this parent up...way up! This is indeed the present human course that will threaten us the most.
What will keep the counterweight in orbit is basic physics. You set the whole thing up so that gravity and conservation of energy and so on work for you.
The question I want to know is what are the osilation modes going to look like. You have a massive string under tention, it is going to vibrate. I'm sure you could figure it out if you had some clue as to the properties of the material.
Erlang Developer and podcaster
Ah, but what about centrifugal force. If his eyes were rolling very fast the resulting heat from the friction would destroy the eye socket and the eyes would simply roll out, no longer secured to the body.
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musings on politics and technol
For these very obvious reasons, the air space around the elevator would be restricted and so would the sea lanes. Remember, this though would be far out in the Pacific, very very far from anywhere (hundreds of miles - not a 15 minute jog). It's not like you could sneak up on the thing.
I'd like to see those Lear Jets that could evade F-16s in any air space, let alone over the open Pacific. It's not like they can pretend to be Clint Eastwood in Firefox and dive down a canyon or something. Shoulder mounted missiles? Fired from where? A guy bobbing in a life preserver who swam out there?
Besides, terrorists could blow up airplanes, mine harbors, poison water supplies, gas subways, fly planes into more buildings, put truck bombs on major bridges or in garages of major business buildings... If we're going to worry about the sky falling, we might as well just hang up our guns and slink off into the sunset.
Quoth he
"It's all academic anyway..."
I live on the fourth floor of an apartment complex and it takes about 3 minutes for the elevator to reach ground floor, another 2 for it go up to the fourth floor. It's faster for me to climb the stairs. How long will it take this thing to go up to the ISS?
Learn something new.
And when we discover life on mars, we'll know the egg came before the chicken.
Ceci n'est pas une sig
Slashdot - Texas Scientists Spin Carbon Nanotube Fiber
Other promising research:
Slashdot - Scientists Crack Silk's Secret
and
Slashdot - Nanotube Applications Grow And Grow
Maybe they did discuss all this and more at the conference - I would like to hope that these scientists and researchers are aware of what is going on in this far-flung field. I only wish they would have made mention of this stuff in the article for the common man, to show that it wasn't all so much "hooey" - that it is something which may be inevitable, and will happen sooner than we all expect.
We (all of mankind) are rapidly moving in a very funky direction, technology-wise. We have carbon-nanotube fibers. We are looking into other advanced fibers and fiber processes. We have found sea-creatures that make insanely great fiber optic fibers (and with the other stuff, we will probably be able to replicate the process very soon). The gains in communications alone will cause a lot of other gains to be made, because of distributed processing amongst far-apart supercomputing centers that need more bandwidth than they already have (and they have a crapload, but not as much as they want or need). Such fibers may help in the optical-computing dept as well. Remember also the stories of "growing diamonds" - that are so pure they are almost impossible to distinguish from real diamonds - and they have DeBeers quaking at the possibilities to their "markets", maybe destroying them. But these companies don't want the diamonds for prettiness or money (well, they want them for the money, true), but to be able to use them for the substrate of computer chips, instead of silicon, for higher speeds and better heat dissipation.
Couple that with all the other "funky" advances we have seen - we are all being dragged in a very wierd direction, speeding up the computing and learning capacity of all involved (and even if you are at the edge of the network, like most of us are here, and not where the action is, you will still be pulled in)...
I don't know where to go with this - except that our current distopia (and if you don't think we are living in a distopia, one every bit as scary, strange, and awe-inspiring as science fiction can come up with - you haven't been paying attention) is going in a new and strange direction, strangely reminiscent of what the "early-years" (which are only touched on) of Neal Stephenson's "Diamond Age" might have been like.
This is all strange shit, yet very few of us are even seeing it or thinking about the real implications, for some reason...
Reason is the Path to God - Anon
Not to mention remote manupulator devices, of the sort often used in nuclear experiments... they're often called "waldoes", a reference to a Heinlein story called, simply, "Waldo", where he introduced the concept.
--Larry
Never attribute to malice that which is adequately explained by incompetence
"I personally hope we continue building what Sci Fi writers write about."
I'm just waiting for my light-saber.
Oh lord not this again. Yes, we must not do anything that may be a target for terrorists. Dont drive your car because there might be a car bomb. Dont fly becuase the plane might be hijacked. Tell you what, why dont you hide under your bed while the rest of us continue on with life and the building of civilization.
I'm a programmer, I don't have to spell correctly; I just have to spell consistently
So even at 100KPH it takes 15 days up or down?
I'd imagine that theme would get old on the way up.
Baaaaaaaa....
Baaadaaaaa....
Baaaaaadaaaaa...
BAAADAAAA BUM BUM BUM BUM BUM BUM BUM
i mean jeez.
You like your new Mac more than you like me, don't you, Dave? Dave? I asked...She said Yes.
For one thing - this is strong stuff we're talking about - incineration is garuanteed. If it breaks up that might sound like an imporovement - but the it's like being shot with a shotgun. It may be loaded with pellets, or it may be loaded with solid rounds. You may spead the impact a little, but its the kinetic energy that'll kill you - and you still get all of that.
Not scared yet? Let's put this in perspective.
according to its website the Golden Gate bridge weighs 380,800,000 kg and spans 1966m. That's probably comparable to the weight/length ratio for a space elevator. It uses hi-tech materials, but it has to support its own weight across its entire length, and its going to be long! According to Nasa (google cache) the elevator is likely reach 36,000,000m. That's 18,311 times the length of the GGB
So taking the golden gate bridge as a guide, we can estimate the total weight of the cable at 18,311 x 380,800,000kg = 6.97 x 10^12. Seven gigatonnes - lighter than I expected.
How hard is it going to hit? Well, at least terminal velocity. I say "at least because the upper reaches will be going faster and have to be slowed by the atmosphere. Also the cable will be considerably denser than a human, so we can reckon it's terminal v as being rather more than a human's. Human terminal v is about 50m/s so let's go with that for the time being. We're being conservative..
Kinetic energy = 0,5 x mass x velocity x velocity
= 6.97294 x 10^12 x 50 x 50 / 2
= 8.716175 x 10^15 joules
And to put that in perspective, one megaton comes to about 4.184 x 10^15 Joules.
So if the cable came crashing down it'd release about 2 Megatons of kinetic energy - either as heat as it burnt up, or as shockwaves on impact.
Doesn't sound like much? Well, the Hiroshima bomb is reckoned as being 20 killotonnes yeild. So 200 hundred hiroshima bombs going off in a ring around the equator in fairly rapid succession.
and it it hits faster than that... well that's a square term. 100m/s give you 4 time the energy or 800 hiroshima bombs. 200m/s (not unreasonable) gives 16 times - 3,200 x hiroshima.
Don't get me wrong - I'd love to see a space elevator. Just let's bear in mind that this is dangerous
Don't let THEM immanentize the Eschaton!
"the floating base platform would be placed hundreds of miles from aircraft routes and shipping lanes and would be in a region of the sea where storms, lightning and high waves are rare." I understand that they are concerned about access, but in reality it's a waste of time and money. Any sufficiently useful transport technology has historically generated growth and traffic around itself. Instead of having to deal with restricted and obscure access routes, these elevators should be dropped into the major trade centers of the world. Ports bring boats, airplanes, highways and trains all into one place. The next logical step is to include access to space. If the space elevator is built in the middle of the pacific ocean, the next great challenge will be to supply a floating airport and direct shipping routes...
How do you gain traction on the cable without damaging it? Just throwing a rope up isn't enough, you need to be able to climb it as well. If you start with a 1m x 0.3m cable, then sloughing even a tiny amount of cable material as you climb or descend is going to chew though it quickly.
If you were blocking sigs, you wouldn't have to read this.
Dude, now the terrorists know about his bed.
Actually, the original article states that the concept "first gained *widespread* attention when the science fiction writer Arthur C Clarke described it in his 1979 novel Fountains of Paradise".
The concept had been invented independently both in USA and the Soviet Union long before the book was written -Arthur C. Clarke's great contribution is bringing the concept to a wider audience. (The cosmonaut Leonov had actually made a painting depicting a space elevator, but westerners -ignorant of the concept studies being done- thought he was nuts)
BTW, I was in contact with ACC two yeras ago and asked him about this novel. He mentioned that the scientist who helped him with the facts was non other than Buckminster Fuller, the discoverer of "buckminsterfullerene".
It so happens that the carbon nanotubes which have the tensile strength to make the cable possible are simply tubular versions of buckminsterfullerene. Fuller himself was not aware of this ironic fact, the nanotubes were only produced in the lab and had their strength measured in the nineties, after Buckminster Fuller's death.
Yours Birger Johansson
From http://www.snopes.com/rumors/pentagon.htm
Anything else I can help you with?
Remember, the Pentagon is a miliatary structure and was MEANT to withstand attack. It's a VERY solid structure.
I would dare say it's built like a fort.
-------- -------- Support Wesley Clark for president!!!
OK, so these folks think they can move the base station to avoid space junk. That sounds extremely tricky already. But I wonder what they can do about meteorites and other smaller stuff that comes in much larger batches? The cable may be able to take one or two hits from these little buggers, but it's going to sustain *some* damage!
Well, we could always use it for propulsion. Make the counterweight a giant shirt and the elevator out of socks and the elevator will shoot right up there.
I'm not shy, I'm stalking my prey
While it has 0 lateral motion WRT the surface, it is still in orbit.
As sections of the cable drop lower, their orbital velocity will increase WRT the ground, and the cable will try to "wrap" itself around the planet.
By the time that most of the cable hits thicker atmosphere, it will be going at a pretty good clip, and will burn up (even the light, "fluttery" ribbon sections).
Here is an experiment that you can try in the safety of your own home to verify this:
- Evacuate all of the air from a room (to prevent stray air currents from skewing the results).
- Drop a ball from a height of, say, 6-10 ft or so.
- Note where the ball landed WRT its release point.
You will see that the ball landed several microns East of its release point (and a few microns toward the equator, as well).A few microns might not sound like much, but multiplied out to 36,000 miles, that's a lot of microns.
Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
It has some obvious mistakes like:
> At about a third of the way along the cable -
> 36,000km from Earth - objects take a year to
>complete a full orbit.
Should be : 24 hour to complete a full orbit
>The biggest hazard could be space junk, but Dr
>Edwards said the floating platform would be moved
>around to steer the cable out of the way
Hmm. I would like to see them:
1. Tracing space junk ~0.01-1mm in size
which flies around with a speed ~10km/sec.
2. Moving platform fast enough on the ground
to avoid collision at the altitude
~200 -1000 km . At those altitudes junk
has the maximum density.
> Edwards, who estimates it would take about $7bn
> (4.4bn) to turn the concept into reality
This thing should weight no less then ISS.
Most of it flies much higher orbit:
36,000-100,000km compare to ~500km for ISS,-
READ: more expensive to get there.
Now check the web about ISS price tag.
Reminds me the story with cheap Space
Shuttle for $5.6 +/- 1.0 bn.
Either article is bad or this guy is full of @#$%.
Pessimist is a well informed optimist.
The Guardian says: "The biggest technical obstacle is finding a material strong but light enough to make the cable; this is where the carbon nanotubes come in." But what about selecting the appropriate carbon nanotubes among the 56 known varieties? Two teams of chemists from Rice University and the University of Illinois at Urbana-Champaign (UIUC) have found a way to separate and manipulate these varieties of carbon nanotubes. Obviously, it will help to build the Space Elevator. More details are available on my blog.