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Oh yes you can use multiple pumps, but the number of pumps you would need would just be completly stupid. A pump would only have the ability to push the gas up a few miles most likly, so you are going to need hundreds or thousands of pumps along the length of the pipeline.
This is absolutely unacceptable because of the weight of all the pumps would require a space elevator of rediculous size to support them, and there is no practical way to power all the pumps because of the electrical resistance in transmitting the the power over that great of a distance. A hundred miles is a long way to make a power line, a line 24,000 miles long is unacceptable. Don't even think about powering each pump with a solar array, the additional weight would be staggering.
Plus, if you pump Xenon up the pipeline, its molecules are so heavy that you would need far more pumps. Maybe one for every mile even, so you are looking at needing tens of thousands of pumps to get any gas to the top. I shudder to think how much energy that would consume to move a kilo of gas.
And if you haven't figured it out after reading 20 pages of me repeating over and over again that the size of the pipe has nothing to do with how high the gas can go, then I don't know how else to say it. If your pipe was a micrometer wide or a kilometer wide, it doesn't matter, the gas will go no higher in either one. If your pipe is only 1/4th of an inch in diameter, you will have so little gas flow that it would be useless. You need to be able to move hundreds or even thousands of kilograms a day for this to be competitive to simply filling a tank and winching it up the elevator.
Oh, and since there is so little Xenon (or Krypton) on Earth, and Ion engines use so little of it, there would be no need to move hundreds of tons a year anyway. The whole pipeline thing is simply a terrible idea.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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How about if it was shaped like a Manometer U shaped but upside down where both open ends are hanging down near the surface? You could put an air ejector on one end and the hydrogen would flow into the other end. Near the top of the U you can tap into the line and get the H2.
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The best point GCNRevenger makes is there is no need to move more fuel to GEO than can be moved by simply winching a fuel tank up a wire. So we are getting way ahead of ourselves here. If a faster rate is desired then more then one tank could go up the wire at once. The mass required to make a space elevator that can pump up a fluid from earth is going to be extreme. This will make a space elevator very unsafe if it falls down. A more reasonable place to make a pipeline might be along a lunar space elevator. As for powering the pumps use a wave guide not a transmission line. The diameter of the pipe matters in the sense that the wider the pipe the faster the liquid can flow due to less viscous friction.
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Errorist is talking about gasses and not liquids though John. As far as putting it on the Moon, the Lunar gravity is still pretty strong and the pipe would have to be much longer, increasing its mass substantially. A good idea to use an RF waveguide for power transmission, but I have doubts that would be a light enough solution either.
The best bet is just to put it in a tank and pull with an electric motor.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Errorist is talking about gasses and not liquids though John.
I think fluid can mean gas or liquid but I will check the dictionary.
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As far as putting it on the Moon, the Lunar gravity is still pretty strong and the pipe would have to be much longer, increasing its mass substantially.
True but I heard a Lunar space elevator could be made out of Kevlar like materials and would only weigh six tons. If the elevator was made out of nanotubes it could support a much greater weight. Still the weight of a lunar pipeline could be extreme and pose a grave danger to any people or equipment bellow.
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Six? Uhhhh no, I think that any elevator of that length will weigh more reguardless what its made of. Alot more. It is, after all, much longer then an Earthly one.
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http://www.universetoday.com/am/publish … html]Lunar Space Ellevator
The advantage of connecting an elevator to the Moon instead of the Earth is the simple fact that the forces involved are much smaller - the Moon's gravity is 1/6th that of Earth's. Instead of exotic nanotubes with extreme tensile strengths, the cable could be built using high-strength commercially available materials, like Kevlar or Spectra. In fact, Pearson has zeroed in on a commercial fibre called http://www.m5fiber.com/magellan/m5_fiber.htm]M5, which he calculates would only weigh 6,800 kg for a full cable that would support a lifting capacity of 200 kg at the base. This is well within the capabilities of the most powerful rockets supplied by Boeing, Lockheed Martin and Arianespace. One launch is it takes to put an elevator on the Moon. And once the elevator was installed, you could start reinforcing it with additional materials, like glass and boron, which could be manufactured on the Moon
Well then this article is wrong. ???
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Ohhh you mean a light weight elevator. If it takes 6.8MT to lift 200kg safely, then it will weigh around 1000MT in order to support two 20MT payloads with climbing equipment, not counting the aluminizing of the cable to prevent radiation damage to the polymer material.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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Ohhh you mean a light weight elevator. If it takes 6.8MT to lift 200kg safely, then it will weigh around 1000MT in order to support two 20MT payloads with climbing equipment, not counting the aluminizing of the cable to prevent radiation damage to the polymer material.
I see the problem. Initially a light one could be made I think. I am not sure if that aluminizing would add too much mass. But you would not want to ship 1000 MT from earth and the moon has no carbon. Maybe you could the extra carbon from an asteroid but I couldn’t see anyone building something on that scale for a thousand years. I do wonder how much weight a lunar pipeline would have to be able to lift to compete with a witched tank. 20 MT?
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Twenty metric tons sounded like a nice round figure for a useful elevator payload, close to the average lift capacity of rockets today. It can't be too small since traversing the cable will take a few days. A ribbon-style elevator as proposed for Earth would have, perhaps, two cable cars operating simultainiously.
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Go ahead and build the light space elevator on the moon. How often are you going to send stuff from the surface anyways? Send everything up in 200 kg packets and build a light 'warehouse' space station at the correct stationary orbit height.
Strange idea: why make a ribbon at all for Earth? Why not build a nice long maglev line on a mountainside for accelerating scramjets? The military can use it to fling bombs when it's not being used for civilian pursuits, and it's a lot more near term than the elevator. Plus, you don't need to locate it near the equator.
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Here is a stab at what kind of tube would be required to lift water to low-orbit via-capillar action. Re-working the equation I showed you earlier you get
r = 2T/Hdg
r = radius
T = Surface tension = 7.29e-2 J/m^2
H = height = 300km
d = density = 1.0 g/ml
g = gravity = 9.8m/s^2
Solving this, you find that you would need a tube an impossible 50pm. Water molecules are about 300pm in diameter. I don't think I need to repeat the excersize for geosyncronus orbit, do I, that's some 34,000km up...
Now while water has just about the highest surface tension of any liquid due to the strong hydrogen bonds bettwen the molecules, the intermetalic bonds in mercury are about an order of magnitude higher (in fact, this is why mercury has a reverse meniscus) 4.6 x 10-1 J/m2. But in anycase, the idea is still impossible.
Also, none of this addresses the problem of how do you get the water out once it has risen to the top. If you just drill in a whole in the tube, the water level just drops down lower. Tree's remove the water via various methods of cellular filtration, I guess you could do something similar, but it's not an easy problem either.
He who refuses to do arithmetic is doomed to talk nonsense.
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Also, none of this addresses the problem of how do you get the water out once it has risen to the top.
You could spin the end, and have the water squirt out due centrifugal force.
High intensity sound waves, and electric charge.
Or, as the tree does it, via evaporation into low relative humidity.
Could thermal quantum effects raise the height ?
I am thinking of molecular size one way valves.
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No MarsDog, trees extract water via osmosis, which is a very slow process on the industrial scale. You still need to be able to move multiple metric tons daily in order to compete with a regular tanks & winch space elevator.
Thanks for doing the number crunching Austin, interesting.
"...thermal quantum effects" Huh? What are those? I don't think there is any way you can cheat gravity to the degree you want to, molecular "one way" valves have to be big enough for the water to rise, in which case they are also big enough for the water to fall again under gravity.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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No MarsDog, trees extract water via osmosis
http://www.bonsai4me.com/AdvTech/ATPhysiology.html]The rise of water in a plant body is caused by root pressure, capillary action, transpiration and cohesion. A tree of 100ft (or more) is only able to supply water to its uppermost branches because the tensile strength of water is very great; that is to say, an enclosed column of water will not break into separate droplets except under enormous tension.
The root pressure is due to osmosis.
If you overfertilize, then the water flows the wrong way, hence yellowing of the leaves.
Some trees can evaporate several hundred gallons per day.
Please note the concept of "tensile strength of water".
The chemical composition of the water flowing up, inside the tree, is the same, untill it reaches the leaves, where the water evaporates. No osmosis or capillary action on the way up, just pulling on a long chain of water molecules.
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Marsdog that is fasinating prehaps a beanstalk could do it if the fibers were just the right size. The only thing we would need to do is keep Jack away from the base of the beanstalk. A Nano tube bean stalk.
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No point to it, Errorist. First off, that property applies to water, which has a variety of odd properties for a liquid of its molecular weight. Second, it wouldn't work to orbital heights.
The biggest problem with the 'pipeline to heaven' is the mass of the liquid in the system, which would quickly prove to be prohibitive. It's far simpler to build a normal elevator with a tanker car of sorts.
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Errorist, have you tried to calculate the weight of a 36,000km high column of water?
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Errorist, have you tried to calculate the weight of a 36,000km high column of water?
Well the pressure is greater then:
rho*g*h=(1 000 kg/m^3)*(9.8/4 m/s^2)*(6 000 000 m)
=1.4700e+010 (kg m/s^2/m^2) or (N/m^2) 0r Pa
=1.4700e+07 Kilopascals
1 Atmosphere is 101.3 Kilopascals
Therefore that is
1.4511e+005 Atmospheres
Thus it will exert more then 15 000 Atmospheres of pressure.
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We have pumps that can pump that amount of pressure (217556.6 psi). Also, Like I said before it can be as little as 5 pumps lacated at different elevations to take away the stresses involved with the pumps.
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okay Errorist, how much will the pipe needed to support this pressure over this height weigh?
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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depends on wall thickness and inside diameter.
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The main problem is that the sheer weight of the liquid in the pipeline is going to be huge. That's one long garden hose, Errorist.
I've just thought of a different, equally crazy idea for getting stuff into orbit cheaply. Instead of building an incredibly long tether, build a ring of inflatable balloon pillars instead, reinforced with aluminum rings every so often, to a height of 150 miles or so. Pressurize the balloons with helium and reinforce them with Kevlar or something and wrap the structure with plastics to make the whole structure airtight. You could evacuate the air from inside the tube, since it's sticking out into LEO, and run a linear magnetic accelerator up the center to accelerate payloads.
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Evacuated balloon tunnel into LEO... well, its one of the more original technical ideas I've heard around here.
The problem with it is that when you get to LEO, you wouldn't have any horizontal velocity, and thats the killer, you need to be going Mach 25 to reach a stable orbit.
And with all railgun ideas, there is no cheap/easy method to pick up payloads when the arrive, and it can't be used for "soft" payloads easily.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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