Carbon nano tube straw for fuel transfer to space

ERRORIST · 2004-02-25 23:49:41

A carbon nano tube straw extended all the out to space from the equator would allow H2 or He to freely rise from the surface of the Earth to fuel stations in geostationary orbit. Just let it in the bottom, and let the differential pressure between the vaccum of space, and the pressure at sea level create the flow.
Any thoughts???

replicant7 · 2004-02-26 03:26:22

Just how strong would this carbon nano-tube straw be ?
Seems as though if it is too fragile then the idea is a non-starter.

GraemeSkinner · 2004-02-26 04:02:14

How would it stand up to winds at different altitudes? When you think of the stresses of not only the winds, but the weight of that height of structure it would need to have some considerable wall strength and bracing just to stand up. Another question I have is how do you construct something that goes through our atmosphere and into space?

ERRORIST · 2004-02-26 07:09:50

Carbon nano tubes are well up to the task. Tensile strength is well within the bounds. It would be held in space by a counter weight. Check out this link it explains the theory well:

[http://science.nasa.gov/headlines/y2000/ast07sep_1.htm]http://science.nasa.gov/headlines/y2000/ast07sep_1.htm

replicant7 · 2004-02-26 07:59:09

sure looks like a whole lot of nano-tubes needed to build it....how long would it take to complete construction if and when started?

ERRORIST · 2004-02-26 08:13:36

Not really the inside diameter is only 1/4".

replicant7 · 2004-02-26 08:37:30

the diameter of the straw is 1/4" ?

ERRORIST · 2004-02-26 09:08:15

The inside is diameter is 1/4 inch.

GCNRevenger · 2004-02-26 10:14:15

Although a neat idea, it won't work... gravity will pull down gasses just as other things, and will prevent the gas from getting very high. Here on Earth we have a large pressure differential between the ground and space, why doesn't our atmosphere immediatly blow away?

ERRORIST · 2004-02-26 10:29:04

Hydrogen, and helium do make it up through the atmosphere all the time if it does not combine with somthing on the way up. Some of it escapes to space, and is carried away by the solar wind.

GCNRevenger · 2004-02-26 17:29:07

Perhaps a small amount but the quantity is very small, hence it wouldn't work very well. Applying extra pressure on the Earthside end would present mechanical concerns for the hose.

ERRORIST · 2004-02-26 17:41:31

You wouldn't need to apply extra pressure.It will flow because of the difference of pressure. Nothing has to be attached at the bottom.

GCNRevenger · 2004-02-26 21:22:49

But, due to gravity, the flow will be unuseably small unless you do... there is quite a bit of Helium still in our atmosphere, or else it would be too rare to fill balloons with.

Rxke · 2004-02-27 04:39:07

The discussion seems moot to me. Current designs for the cable use a ribbon (well, several, eventually), not a tube-like structure.... That way, micro metoroids can make small holes, not a problem. A straw getting punctured would be the end of the story.

Of course, you could make ribbons out of a bunch of straws, but again... in the end it will be a very leaky affair after a short while...

ERRORIST · 2004-02-27 06:13:03

Well, the smaller it is the less chace it has for being hit. Also,it can be protected from being hit with a shielding that is not attached.

Shaun Barrett · 2004-02-27 06:40:39

GCNR is quite correct. Molecules of H2 or atoms of He are subject to Earth's gravitational pull whether they're inside a carbon tube or not.
If you measured the pressure of gas in the tube at ever greater heights above Earth's surface, you would notice that pressure reducing in exactly the same way as the air pressure outside the tube reduces with altitude.
Even at the modest height of, say, 200 km above the ground, there'd be precious little H2 or He exiting the top of your tube. At geosynchronous orbit, the amount coming out would be vanishingly small.

As for the amount of helium in our atmosphere, a quick google reveals there is 0.0005%, while the amount of hydrogen is only 0.00005%.
Isolating helium from the air is not normally commercially viable at these low concentrations but there is often a much higher percentage of helium in natural gas. For example, in the U.S.A. the concentration of helium in natural gas is as high as 7%. Just about all of this helium arises out of the natural radioactive decay of heavier elements in Earth's interior. Earth's original inventory of helium, dating back to the birth of the solar system, has long since been lost.

ERRORIST · 2004-02-27 08:10:46

Ah, but it still proves these gasses rise up, and they eventually make it to space even without the tube as long as it does not combine with other atoms on the way. The solar wind then carries them away. For H2 to make it all the way up is hard to do because it is a hungy molecule, and will combine with just about anything in our atmosphere. As long as there is a pressure difference between space,and sea level a flow will occur. Pressure difference = flow. Gravity does not hold these molecules to Earth. If it did then they would not make it to space.

GraemeSkinner · 2004-02-27 09:34:43

Pressure difference = flow. Gravity does not hold these molecules to Earth. If it did then they would not make it to space.

Gravity would have an effect on this process of 'pressure difference = flow'. As molecules will be acted upon by gravity, the force acting upon those molecules from the pressure difference would have to be greater than that of gravity.

ERRORIST · 2004-02-27 09:57:30

I agree but the force of gravity alone is not great enough to confine these elements to Earth. If it was, then they would not escape to space. The concentration of the H2 or He in the tube would be near 100%. The concentration of H2 or He outside the tube is far less than 1%. Therefore, they have nothing to combine with inside the tube, and will flow freely to space.

GraemeSkinner · 2004-02-27 10:57:18

This is not an area I have studied recently, but surely the molecules that naturally escape from say the exosphere do so because they have enough kinetic energy to reach an escape velocity. The kinetic energy here would I presume come from either collision with other molecules, or the suns thermal influence upon them. Molecules within the tube at ground level would not have the same influences upon them, plus at lower levels the kinetic energy they'd require would be greater to counteract the amount of gravity acting upon them. I'm not sure the physics work out that the molecules would automatically fly upwards into space, my view would be that the upper segment of tube if filled with these two molecules alone would empty into space and a vacuum would form above the lower molecules and there they would stay with only a slight escape of the upper molecules.
As I say my knowledge of physics in this area is a little rusty (it's two years since I studied gravity, and four since I studied the interaction of any molecules.) If it does work I'll be quiet happy to say woops I got it wrong, pass me a edible hat

ERRORIST · 2004-02-27 11:19:02

So, whatever amount escapes from the top no matter how small, is also being resupplied at the bottom. Therefore, a continious flow is occuring. Now it becomes a volume problem. How much is actually escaping and at what rate? Frictional losses,tube diameter, diffential of pressure, and heat losses all have to be calculated. BTW what flavor hat do you like, and what is your address so I can send you one? Don't take me seriously just messing with ya!!!

dicktice · 2004-02-27 11:48:31

Messing about with physics just won't do, Errorist! Perform a little work, and calculate the height of a column of hydrogen gas supported by 15 lb/sq in, inside a hypothetical open-ended "barometer tube" extending out beyond the atmosphere. Then get back to me/us.

ERRORIST · 2004-02-27 12:02:27

I have seen the effects of this already working. The physics already work in a tall smoke stack. Air comes in the bottom and air goes out the top. Prove me wrong???? The same will work with H2 out this long tube extended into space. Also, you can't calculate 15 psi per sq/in through out the whole column as the pressure changes with altitude. BTW I was messing with GraemeSkinners hat, and not the physics portion.

GraemeSkinner · 2004-02-27 13:54:09

The smokestack is a different situation, for one energy is supplied at the base of the stack (by whatever is creating the smoke). Also the height of smokestacks are tiny compared to the nano tube straw idea.
A marzipan hat would be fine :up:
Graeme

ERRORIST · 2004-02-27 14:01:27

The smokestack theory works. Natural circulation occurs because of the temperature difference between the two elevations.

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#1 2004-02-25 23:49:41

Re: Carbon nano tube straw for fuel transfer to space

#2 2004-02-26 03:26:22

Re: Carbon nano tube straw for fuel transfer to space

#3 2004-02-26 04:02:14

Re: Carbon nano tube straw for fuel transfer to space

#4 2004-02-26 07:09:50

Re: Carbon nano tube straw for fuel transfer to space

#5 2004-02-26 07:59:09

Re: Carbon nano tube straw for fuel transfer to space

#6 2004-02-26 08:13:36

Re: Carbon nano tube straw for fuel transfer to space

#7 2004-02-26 08:37:30

Re: Carbon nano tube straw for fuel transfer to space

#8 2004-02-26 09:08:15

Re: Carbon nano tube straw for fuel transfer to space

#9 2004-02-26 10:14:15

Re: Carbon nano tube straw for fuel transfer to space

#10 2004-02-26 10:29:04

Re: Carbon nano tube straw for fuel transfer to space

#11 2004-02-26 17:29:07

Re: Carbon nano tube straw for fuel transfer to space

#12 2004-02-26 17:41:31

Re: Carbon nano tube straw for fuel transfer to space

#13 2004-02-26 21:22:49

Re: Carbon nano tube straw for fuel transfer to space

#14 2004-02-27 04:39:07

Re: Carbon nano tube straw for fuel transfer to space

#15 2004-02-27 06:13:03

Re: Carbon nano tube straw for fuel transfer to space

#16 2004-02-27 06:40:39

Re: Carbon nano tube straw for fuel transfer to space

#17 2004-02-27 08:10:46

Re: Carbon nano tube straw for fuel transfer to space

#18 2004-02-27 09:34:43

Re: Carbon nano tube straw for fuel transfer to space

#19 2004-02-27 09:57:30

Re: Carbon nano tube straw for fuel transfer to space

#20 2004-02-27 10:57:18

Re: Carbon nano tube straw for fuel transfer to space

#21 2004-02-27 11:19:02

Re: Carbon nano tube straw for fuel transfer to space

#22 2004-02-27 11:48:31

Re: Carbon nano tube straw for fuel transfer to space

#23 2004-02-27 12:02:27

Re: Carbon nano tube straw for fuel transfer to space

#24 2004-02-27 13:54:09

Re: Carbon nano tube straw for fuel transfer to space

#25 2004-02-27 14:01:27

Re: Carbon nano tube straw for fuel transfer to space

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