Space Elevators and Pipelines

RobertDyck · 2004-11-23 15:16:46

Carbon nanotubes/nanofibres are the only material with a strengh:weight ratio sufficient to hold its own weight that far without breaking. What happens when you add the weight of a column of gas for the entire length? Would it exceed any possible tensile strength? Remember, with multiple pump stages the gas weight is not sitting on the ground, it's sitting on pumps which are attached to the cable.

John Creighton · 2004-11-23 15:16:59

Also, the efficency for the whole pump idea is going to be pretty lousy, since you trying to "throw" up the gas molecules in steps, and since not all will make it then alot of the energy will be lost to thermal effects. A payload in a tank however, the energy conversion will be much better.

I’ll debate efficiency later. The system could lose energy when the pumps compress the gas in terms of heat but it may get that heat back through the sun. Anyway, I don’t know if efficiency is the main issue. Electricity is pretty cheep (5 cents per kilowatt hour). The main issue is enough throughput to offset the fixed costs.

GCNRevenger · 2004-11-23 15:19:51

You must take into account all aspects of the interaction with gas molecules with the walls of the pipe and themselves, plus provisions for their mass, their density, and so on. Perhaps kenetic velocity too. Models without these facets on this scale, just one thing ignored or glossed over can make all the difference.

GCNRevenger · 2004-11-23 15:23:14

Carbon nanotubes/nanofibres are the only material with a strengh:weight ratio sufficient to hold its own weight that far without breaking. What happens when you add the weight of a column of gas for the entire length? Would it exceed any possible tensile strength? Remember, with multiple pump stages the gas weight is not sitting on the ground, it's sitting on pumps which are attached to the cable.

The idea is that the "excess" tensile strength of the cable in supporting its own weight would be used to mount whatever cable car or pipeline system.

One idea, is a "vertical conveyer belt," where a loop of cable or a ribbon is run in a cycle continuously, and as many cars as the cable supports run up simultainously without climbing mechanism, just a latch. The lifting would be done by the station(s) at the end(s).

John Creighton · 2004-11-23 15:28:48

Your right that with a lot of stages of pumps you would have to support the weight with Carbon nanotubes. If you had a big first stage then you could have a lot of the column force supported by the ground. I figured 80 bars of pressure could get 0.5 bars of air 2880 km. To figure out the weight for the first 2880 km you multiply the pressure by the area. So if the pipe had an area of 10 centimeters squared the weight of the gas in the first 2880 km would be:

80(atmospheres)*101 e3 (Pa/atmosphere)*(0.001 m^2)= 8080N
Giving an effective weight of:
8080N/(9.8m/s^2)= 824.4898 Kg

Now this is a rough estimate for the first 2880 km. Remember after 6000Km (The radius of the earth) gravity drops by ¼. So The effective weigh for the first 3000 km would be less and the gas in the tube much past 6000 km will hardly have to be supported at all.

GCNRevenger · 2004-11-23 15:39:49

But, that is a pretty small pipe. 80ATM of pressure is also awfully high to put Hydrogen in contact with unprotected carbon for extended periods, especially if heated by sunlight and compression.

John Creighton · 2004-11-23 15:40:50

You must take into account all aspects of the interaction with gas molecules with the walls of the pipe

This could be the biggest hindrance to flow rates for a small tube. The roughness in pipes is known to inhibit flow at smaller scales this becomes more significant. That is why I asked how smooth the pipe will be. Anyway I am currently thinking of a pipe with a 10 cm^2 cross section. The weight of the pipe will depend on how much pressure it must withstand. Unfortunately some of the nanotubes will have to be wrapped around the pipe to support the pressure. These nanotubs will not be able to support the vertical loads. Fortunately nanotubes are light.

SpaceNut · 2004-11-23 19:48:24

Make chambers at given intervals of height, which open and close to allow for movement due to pressure changes, one could also heat the air that is in the lower chambers to increase the released vented pressure build up to the next one. Kind of like the panama canal lockes.

John Creighton · 2004-11-24 09:18:31

Anyway I think the mass flow in kg/s is given by pho*A*v. (I will double check this later). So consider methane and a 10 cm^2 pipe with the gas going at 20 km per hour. We have:
(0.0006557e3 kg/m^3)*(0.001 m^2)*(20 km/h * (60^2 s/1000 m))
=0.0472 kg/s *(60^2*24 s/day)
=4.0790e+003 kg/day *(355 day/year)
=1.4480e+006 kg/year
That is 145 tons per year. I haven’t worked out the effect of friction yet. Compared to the shuttle which delivers 20 tons for 200 million (some say a billion) that is about 10 million dollars per ton. At about 10% borrowing costs and neglectable operating costs as long as the system cost 1.440 billion it would be economical. Thus the system will probably need to have a greater mass flow then 0.0472 kg/s to be economical unless it can built extremely cheep.

MarsDog · 2004-11-25 14:24:09

Assume 1 meter outer radius tube, suspended from geosynchronous.

Vary the inside diameter of tube, optimized for http://hyperphysics.phy-astr.gsu.edu/hb … l]pressure at the bottom.
At the top, for strength to support the pipe below.

No closed form solution exists.
No way around numerical http://www.zadar.net/space-elevator/#Ca … ntegration.

You could neglect the Sun and the Stars, but should include the Moon.

John Creighton · 2004-11-26 09:12:32

Awesome link Marsdog. Anyway if I understand the sight right each cable they are considering starts with a diameter of 1 cm. For carbon nanotubes, this cable could support 1200 tons and there supper cable could support 168 tons. I think the supper table is made out of: Zylon (PBO, plastic fiber) which has a weight to strength ratio of 2.71*10^-7 (s^2/m) and carbon nanotubes have a strength to weight ratio of 8.67*10^-9 (s^2/m). The volume of the cable starting with a 1 cm diameter is given by the following graph:

For carbon nanotubes the total volume would be 10 000 m^3. The density of carbon nanotubes is 1.3*10^3 9 Kg/m^3. Therefore the total mass of the cable is:
(10 000 m^3)*(1.3*10^3 kg/m^3)=13 000 000 kg or 13 000 tons. At 10 million per ton the cost to lift the cable would be 130 000 000 000 000 or 130 trillion dollars. At a 10% financing rate the cable would have to move 13 trillion dollars worth of mass to orbit per year. If they payload was worth 10 million per ton. Each trip the elevator could lift 10.2 billion dollars worth of payload. So the cable would need to make (13e15/10.2e12)=1 300 trips per year or 3.65 trips per day. I don’t think this will be economical until we either have a cheaper way to lift mass to orbit (maybe a scram jet) or we discover a carbonous asteroid very near earth. I wonder if the first carbonous asteroid will be the black gold of space.

For the cable to be economical by using earth resources we will need launch costs to be at least 1000 times cheaper by some method other then a space elevator.

John Creighton · 2004-11-26 16:37:12

http://www.ioncmaste.ca/homepage/resour … pdf]Carbon asteroids comprise about three quarters of all the asteroids and
are dim with non-reflective surfaces. Silicate asteroids ...

Astronomers using data from the Sloan Digital Sky Survey found that the solar system contains about 700,000 asteroids big enough to destroy civilization. That figure is about one-third the size of earlier estimates, which had put the number at around two million and the odds of collision at roughly one in 1,500 over a one hundred-year period.
"Our estimate for the chance of a big impact contains some of the same uncertainties as previous estimates, but it is clear that we should feel somewhat safer than we did before we had the Sloan survey data," said lead researcher Zeljko Ivezic of Princeton University.
The results were published in the November issue of the Astronomical Journal.
The new estimate draws on observations of many more asteroids, particularly small faint ones, than were available in previous impact risk estimates, said Ivezic. The ability to detect faint objects in large numbers is a hallmark of the Sloan survey, a multi-institutional collaboration that is mapping one-quarter of the sky. While its main purpose is to look at objects outside our galaxy, the survey also records images of closer objects that cross the view of its telescope, which is located at the Apache Point Observatory in New Mexico.
The survey data also allowed the astronomers to gauge the size of asteroids with improved accuracy, which required categorizing the objects by their composition. Asteroids with a surface of carbon -- looking like giant lumps of coal -- are darker than those made of rock. http://www.williams.edu/Astronomy/jay/c … tu6.html]A small rocky asteroid therefore looks just as bright as a much larger one made of carbon.

http://abob.libs.uga.edu/bobk/ccc/cc110801.html]Another valuable piece of information for scientists is the bservation that the rock and carbon asteroids are separated into two bands, said co-author Tom Quinn of the University of Washington. The heart of the rocky asteroid belt is 260 million miles from the sun, while the other is 300 million miles from the sun. The sun and earth, by comparison, are 93 million miles apart.

http://abob.libs.uga.edu/bobk/ccc/cc110 … nd-studded Rocks
Ureilites may be the most mysterious of all the meteorites. They were named for Novo Urei, a small rock that fell in Russia in 1886. Until people started collecting meteorites in hot and cold deserts, only six ureilites were known. All contained small grains of diamond (a high-pressure form of carbon), along with graphite (low-pressure carbon). This was a startling discovery because diamonds form at high pressure. Many scientists proposed that the diamonds formed deep inside a large body. But as we understood the effects of large impacts, it became clear that the diamonds were the products of high-pressure shock waves caused by a large impact event on the ureilite body. The key question became the source of the diamond. Was it originally present in the rocks as graphite that crystallized along with the silicate minerals, and was then converted to diamond by shock? Or was the diamond forcibly injected into the rocks by an impact event?
During the past 15 years or so, the number of ureilites has increased dramatically from only six to 110. Some of the new ones are not severely damaged by shock and preserve the original state of the rock and its carbon minerals. Examination showed that they contain long lath-shaped crystals of graphite intergrown with the silicate minerals. The intergrowth clearly indicates that the carbon was not mixed in by a shock event. The original six ureilites fell into distinct groups on the basis of the amount of FeO (iron oxide) in their olivine and pyroxene. This suggested that the rocks within a group were related to each other, but unrelated to the other groups. Analyses of the new samples indicate something ifferent, that there is a complete gradation in the amount of FeO, not separate groups. The relationships among the ureilites are not so simple and researchers are continuing to try to understand the geologic processes on the ureilite parent body.

One group of asteroids dominates the outer part of the belt. These asteroids are rich in carbon. Asteroids in the second group, which are located in the inner part of the belt, are rich in minerals. These asteroids formed from melted materials.

http://www.google.ca/search?q=cache:xO5 … ...2&hl=en

John Creighton · 2004-11-26 16:59:32

How?
With great difficulty. Building cities in space will require materials, energy, transportation, communications, life support, and radiation protection.
Materials. Launching materials from Earth is very expensive, so bulk materials should come from the Moon or near-Earth asteroids where gravitational forces are much less, there is no atmostphere, and there is no biosphere to damage. Our Moon has large amounts of oxygen and metals, but little hydrogen, carbon, or nitrogen. Near-Earth asteroids contain substantial amounts of metals, oxygen, hydrogen and carbon. Asteroids contain some nitrogen, but not necessarily enough to avoid major supplies from Earth

from:http://www.beyondearthorbit.org/bringspacetoschools/Space%20Resources%20and%20Web%20Sites.htm]SPACE RESOURCES AND WEB SITES

One candidate for a major improvement in manufacturing technology is molecular nanotechnology. An important branch of nanotechnology is concerned with developing diamonoid mechanosynthesis. This means building things out of diamond-like materials placing each atom at a precise location (ignoring thermal motion). Diamond is 69 times stronger than titanium for the same weight and is much stiffer. If spacecraft were made of diamonoid materials rather than aluminum, they could be much lighter allowing more payload. For an excellent analysis applying nanotechnology to space development see McKendree 1995.
Diamond mechanosynthesis may enable a radical transportation system that could allow millions of people to go to orbit each year -- an orbital tower. An orbital tower is a structure extending from the Earth's surface into orbit. To build an orbital tower, start construction at geosynchronous orbit. Extend the tower down towards Earth and upwards at the same rate. This keeps the center-of-mass at geosynchronous orbit so the tower stays over one point on the Earth's surface. Extend the tower all the way to the surface and attach it. Then an elevator on the tower can move people and materials to and from orbit at very low cost. There are many practical problems with orbital towers, but they may be feasible.
An orbital tower is in tension so it won't collapse, but it must be very strong or it will break. The point of greatest strain is at geosynchronous orbit, so an orbital tower must be thickest at that point. The ratio of the diameter of the tower between geosynchronous orbit and the ground is called the taper factor. For steel, the taper factor is greater than 10,000 making a steel orbital tower completely impractical. However, for diamonoid materials the taper factor is 21.9 with a safety factor according to McKendree 1995. Thus, a diamonoid orbital tower 1 meter thick at the ground would be only 22 meters thick at geosynchronous orbit. Fullerene nanotechnology, using carbon nanotubes, may be even better than diamond allowing a smaller taper factor. Calculations suggest that the materials necessary for construction of such an orbital tower would require one asteroid with a radius between one and two kilometers. These calculations assume the tower is built from diamonoid material with a density of 4g/cm^3 and the asteroid has a density of 1.8 g/cm^3 and is 3% carbon.
Thus, molecular nanotechnology may enable space settlement.

John Creighton · 2004-11-26 17:08:40

http://neo.jpl.nasa.gov/index.html]Asteroid (4179) Toutatis to Pass Closely By Earth on Wednesday, September 29, 2004

Orbit diagram of Asteroid 4179 Toutatis
Diagram by P.W. Chodas (JPL/Caltech)
Don Yeomans
Paul Chodas
NASA's Near Earth Object Program Office
September 27, 2004
Toutatis, a potato-shaped asteroid about 4.6 km (3 miles) in its longest extent, will pass within 1,550,000 km (963,000 miles) of the Earth's center on Wednesday, September 29, 2004 - reaching its closest approach at 13:35:28 GMT (06:35:28 PDT). This is roughly four times the distance from the Earth to the moon and closer than this asteroid has come to Earth since at least the twelfth century. Toutatis will not pass this closely again for the next 500 years. The passage is the closest Earth approach this century for a known asteroid of this size. Because of an extensive set of optical and radar observations, the orbit for Toutatis is one of the best determined of any asteroid and there is no chance that this object will collide with the Earth during this encounter - or any other encounter for at least 5 centuries.

John Creighton · 2004-11-26 17:12:00

http://neo.jpl.nasa.gov/neo/groups.html]Amors Earth-approaching NEAs with orbits exterior to Earth's but interior to Mars' (named after asteroid 1221 Amor). a>1.0 AU, 1.017<q<1.3 AU

http://neo.jpl.nasa.gov/neo/resource.html]NEAR-EARTH OBJECTS AS FUTURE RESOURCES

The comets and asteroids that are potentially the most hazardous because they can closely approach the Earth are also the objects that could be most easily exploited for their raw materials. It is not presently cost effective to mine these minerals and then bring them back to Earth. However, these raw materials could be used in developing the space structures and in generating the rocket fuel that will be required to explore and colonize our solar system in the twenty-first century. It has been estimated that the mineral wealth resident in the belt of asteroids between the orbits of Mars and Jupiter would be equivalent to about 100 billion dollars for every person on Earth today. Whereas asteroids are rich in the mineral raw materials required to build structures in space, the comets are rich resources for the water and carbon-based molecules necessary to sustain life. In addition, an abundant supply of cometary water ice could provide copious quantities of liquid hydrogen and oxygen, the two primary ingredients in rocket fuel. It seems likely that in the next century when we begin to colonize the inner solar system, the metals and minerals found on asteroids will provide the raw materials for space structures and comets will become the watering holes and gas stations for interplanetary spacecraft.
Reference: Lewis, John S. Mining the Sky: Untold Riches from the Asteroid, Comets, and Planets. Addison-Wesley, 1996.

John Creighton · 2004-11-26 17:21:15

Asteroid Diameter Mass Rotation Distance from Sun Orbital
Period -- Period --
(kg) (10^15 kg) Day (hours) (A.U.) Year (years)
1 Ceres 960 x 932 870,000 9.075 2.767 4.60
2 Pallas 570 x 525 x 482 318,000 7.811 2.774 4.61
3 Juno 240 20,000 7.210 2.669 4.36
4 Vesta 530 300,000 5.342 2.362 3.63
45 Eugenia 226 6,100 5.699 2.721 4.49
140 Siwa 103 1,500 18.5 2.734 4.51
243 Ida 58 x 23 100 4.633 2.861 4.84
433 Eros 33 x 13 x 13 6.69 5.270 1.458 1.76
951 Gaspra 19 x 12 x 11 10 7.042 2.209 3.29
1862 Apollo 1.6 0.002 3.063 1.471 1.81
2060 Chiron 180 4,000 5.9 13.633 50.7

From:
http://home.cwru.edu/~sjr16/advanced/as … eroid.html

patrick · 2004-11-26 17:24:09

Hey so what is wrong with a 1/4 diameter Nanotube pipeline to space?

John Creighton · 2004-11-26 17:39:59

Hey so what is wrong with a 1/4 diameter Nanotube pipeline to space?

1/4 what? 1/4 of a centermeter? For it to be affordable it would probably have to be that small. The problem is for it to be economical it has to have considerable mass flow. That is why I posted some stuff on asteroids. Does anyone know if Eros or Apollo have much carbon. They seem to be the only close asteroids in the table I provided.

patrick · 2004-11-26 17:46:30

Yep, a 1/4" pipeline????? 1/4 INCH

John Creighton · 2004-11-26 17:48:13

I just started a new discussion on Eros.
http://www.newmars.com/forums/viewtopic … ]Encounter with Eros:

John Creighton · 2004-11-26 17:51:17

Yep, a 1/4" pipeline?? INCH

In the above cite the cable had a diameter of one cm. If the 1/4" pipeline had a considerably smaller area then the cable mentioned above then it might be affordable. Calculate how think the walls would have to be for a 1/4" pipe made of carbon nanotubes supporting 90 bars of pressure.

patrick · 2004-11-26 17:51:56

Lets figure out the pipeline first then we can go to Eros????

patrick · 2004-11-26 17:53:52

Calculate how think the walls would have to be for a 1/4" pipe made of carbon nanotubes supporting 90 bars of pressure.

I would think alot thinner than a pipeline with a larger diameter.

John Creighton · 2004-11-26 17:55:56

Calculate how think the walls would have to be for a 1/4" pipe made of carbon nanotubes supporting 90 bars of pressure.
I would think alot thinner than a pipeline with a larger diameter.

But the question is if the total area of horizontal cross section of the walls is less then 1/cm^2. Otherwise you pipe/cable will cost trillions to build.

John Creighton · 2004-11-26 17:57:12

This doesn't sound good.

Despite what meteoriticists have learned about the early solar system, the asteroids themselves remain precious little more than points of light in the sky to telescopic observers. It is generally agreed that the more than 5000 known asteroids are mostly shattered remnants of a much smaller number of larger "parent" bodies. Spectroscopic surveys of the several hundred brightest asteroids show that their compositions differ, and that different asteroid compositions dominate different regions of the solar system. The dominant type in the outer solar system is C asteroids, low albedo bodies thought to be rich in carbon compounds. S asteroids, made of metal and silicate minerals like those of most meteorites, dominate the inner solar system.

http://home.cwru.edu/~sjr16/advanced/as … eroid.html

New Mars Forums

Announcement

#26 2004-11-23 15:16:46

Re: Space Elevators and Pipelines

#27 2004-11-23 15:16:59

Re: Space Elevators and Pipelines

#28 2004-11-23 15:19:51

Re: Space Elevators and Pipelines

#29 2004-11-23 15:23:14

Re: Space Elevators and Pipelines

#30 2004-11-23 15:28:48

Re: Space Elevators and Pipelines

#31 2004-11-23 15:39:49

Re: Space Elevators and Pipelines

#32 2004-11-23 15:40:50

Re: Space Elevators and Pipelines

#33 2004-11-23 19:48:24

Re: Space Elevators and Pipelines

#34 2004-11-24 09:18:31

Re: Space Elevators and Pipelines

#35 2004-11-25 14:24:09

Re: Space Elevators and Pipelines

#36 2004-11-26 09:12:32

Re: Space Elevators and Pipelines

#37 2004-11-26 16:37:12

Re: Space Elevators and Pipelines

#38 2004-11-26 16:59:32

Re: Space Elevators and Pipelines

#39 2004-11-26 17:08:40

Re: Space Elevators and Pipelines

#40 2004-11-26 17:12:00

Re: Space Elevators and Pipelines

#41 2004-11-26 17:21:15

Re: Space Elevators and Pipelines

#42 2004-11-26 17:24:09

Re: Space Elevators and Pipelines

#43 2004-11-26 17:39:59

Re: Space Elevators and Pipelines

#44 2004-11-26 17:46:30

Re: Space Elevators and Pipelines

#45 2004-11-26 17:48:13

Re: Space Elevators and Pipelines

#46 2004-11-26 17:51:17

Re: Space Elevators and Pipelines

#47 2004-11-26 17:51:56

Re: Space Elevators and Pipelines

#48 2004-11-26 17:53:52

Re: Space Elevators and Pipelines

#49 2004-11-26 17:55:56

Re: Space Elevators and Pipelines

#50 2004-11-26 17:57:12

Re: Space Elevators and Pipelines

Board footer