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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
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:
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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.
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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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.
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!"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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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
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!
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!
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?
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!
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.
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. ==> *
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?
The same way that NASA came up with the budget for the space program in the early 50's and 60's. They had to create a huge number of things that did not exist in order to put a man on the moon. From things as mundane as food and drink and holders that could be used while weightless to as science fictiony as computers small enough to fit in an Apollo space craft. Somehow they managed to not only do all of that, but to budget for it as well. Not only that, all of that R&D was very good for the economy, returning, depending on who you believe, as much as $7 to the economy for every dollar spent.
In my universe I'm perfectly normal, it's not my fault you don't live in my universe.
...about the space elevator is when the kid who launched his satellite just before you mashes every button before getting off.
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
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!
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.
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.
Well maybe China's plans to take up residence on the moon will motivate american politicians to take space seriously again.
You'd be basically creating the largest "short" ever.
Not unless you made it out of superconducters! Even the best conductor we know is going to have a significant amount of resistance along the kinds of lengths we're talking about.
And depending on the exact carbon nanotube technology they settle on, the elevator won't be all that conductive to start with... it could very well end up being less conductive than the air around it...
I am disrespectful to dirt! Can you see that I am serious?!
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.
Dude, now the terrorists know about his bed.