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Mars colonization versus Stanford Torus
Regarding the below, perhaps I should more open-minded about the possibility
of Martians selling nitrogen to orbital habitats. K. Eric Drexler discusses this very possibility here (http://www.foresight.org/nano/Mars.html), and this in an article which is otherwise very critical of Mars as a location for settlement. "Mike Combs" wrote in message news:... "John Savard" wrote It just seems to me that there is still a definite advantage of Mars over the Earth as the supplier to space habitats of resources in short supply on the Moon. The right question to ask is not which is better, Mars or the Earth. The right question is which is the best source of all those potentially available. We shouldn't leave out the NEAs. On a travel-time basis they're comparable to Mars. But the clincher is their shallow gravity wells. CC-types will definitely supply all the carbon one could want. Hydrogen would exist certainly in the form of hydrated minerals and potentially in the form of deep core ice. Nitrogen would probably require a bit of digging and processing, but I think avoiding the gravity levy associated with the Martian gravity well would pay for a good deal of processing. Where nitrogen is concerned, I think there are sources available short of Oort cloud frozen amonia, or the atmosphere of Titan. -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#2
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Mars colonization versus Stanford Torus
Mike Combs wrote: Regarding the below, perhaps I should more open-minded about the possibility of Martians selling nitrogen to orbital habitats. K. Eric Drexler discusses this very possibility here (http://www.foresight.org/nano/Mars.html), and this in an article which is otherwise very critical of Mars as a location for settlement. He quotes: The martian atmosphere does contain about 2.5 percent nitrogen - an element rare in asteroids. Thus, it may someday prove desirable to build a polar processing plant to concentrate nitrogen (by freezing out carbon dioxide) and to ship it into space. There, it would find use as an oxygen diluent in the atmosphere of large-scale settlements. Earth's atmosphere is some 79% nitrogen, which seems more promising than Mars' 2.5%. If we need Nitrogen in large quantities* then scooping it out of the Earth's upper atmosphere might be a better bet. *Note, requirements are approx: Mini torus: 240 tons Stamford Torus: 24,000 tons 4km diameter, 12km long O'Neill cylinder, 1 Bar: 120 million tons I susepct by the time we have the Stamford Torus we'll have rotovators able to throw up 60 tons of every 30 minutes. Atmospheric scooping could get something similar. |
#3
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Mars colonization versus Stanford Torus
"Alex Terrell" wrote in message
oups.com... 4km diameter, 12km long O'Neill cylinder, 1 Bar: 120 million tons I noticed you were citing 1 Bar for the atmosphere of an O'Neill Cylinder. It's true that is the assumption in O'Neill's first paper in Physics Today (http://members.aol.com/oscarcombs/TCoS.html), but it's an assumption that he later called "naive". He later recommended an atmosphere of 1/2 the pressure, with the percentage of oxygen doubled, and the percentage of nitrogen reduced accordingly. That not only reduces the pressure load on the structure by half, it significantly reduces the amount of nitrogen we need, first by a half, and then further by reducing the relative percentage. -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#4
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Mars colonization versus Stanford Torus
Good point,
0.2 Bar Oxygen 0.3 Bar Nitrogen 3/8 the nitrogen requirement. I did a quick analysis on a "Profac" base. This would be suspened from an orbiting mother ship and fly through the upper atmosphere at some 6km / second, scooping and liquifying air. A 5m diameter scoop, flying at 85km altitude, could capture 100 tons per day of air, or about 80 tons per day of nitrogen. This would be enough for a Stamford Torus after 1 year of operation. Unfortunatley, an O'Neil cylinder, even at lower pressure, still needs some 1500 years of operation. Of course, the technology would be scalable and repeatable. |
#5
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Mars colonization versus Stanford Torus
"Alex Terrell" wrote in message
oups.com... I did a quick analysis on a "Profac" base. This would be suspened from an orbiting mother ship and fly through the upper atmosphere at some 6km / second, scooping and liquifying air. A 5m diameter scoop, flying at 85km altitude, could capture 100 tons per day of air, or about 80 tons per day of nitrogen. This would be enough for a Stamford Torus after 1 year of operation. What do you plan to use for heat exchange? There'll be a lot of heat associated with the ram intake, and then you have to get from that to (mild) cryogen temps, and fairly quickly. Unfortunatley, an O'Neil cylinder, even at lower pressure, still needs some 1500 years of operation. Of course, the technology would be scalable and repeatable. I'll tell you what I always tell people abou the O'Neill Cylinder. We don't have to worry about building it because it won't be built by Earth civilization. It will be built by a future space-based civilization which will get its start in much more modest habitats. By the time they're ready to graduate up to an Island 3, material from the outmost parts of the asteroid belt will be available, and that might include decent amounts of ammonia ice. If not, we might even be harvesting material from the Trojans by that point, and they should be a lot "juicier" than Main Belt asteroids. -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#6
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Mars colonization versus Stanford Torus
Mike Combs wrote: "Alex Terrell" wrote in message oups.com... I did a quick analysis on a "Profac" base. This would be suspened from an orbiting mother ship and fly through the upper atmosphere at some 6km / second, scooping and liquifying air. A 5m diameter scoop, flying at 85km altitude, could capture 100 tons per day of air, or about 80 tons per day of nitrogen. This would be enough for a Stamford Torus after 1 year of operation. What do you plan to use for heat exchange? There'll be a lot of heat associated with the ram intake, and then you have to get from that to (mild) cryogen temps, and fairly quickly. That is indeed the biggest challenge. I estimated the average surface temperature at 740 degrees C. However, the intake would probably be much hotter (1500 C) so the back end with the compressors could be easier. The original proposal for PROFAC had a nuclear reactor and an ion engine. My idea is to have it suspended on tethers, which also supply electricity, so no need for the engine or the power plant. |
#7
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Mars colonization versus Stanford Torus
"Alex Terrell" :
The original proposal for PROFAC had a nuclear reactor and an ion engine. My idea is to have it suspended on tethers, which also supply electricity, so no need for the engine or the power plant. TANTAAFL - What do you think happen when a tether genarates electric power? The tether's orbit starts to drop as the energy has to come from somewhere. No nuke/solar for power means you are going to crash and darn soon too! Earl Colby Pottinger -- Cruising, building a Catamaran, Rebuilding Cabin, New Peroxide Still Design, Writting SF, Programming FOSS - What happened to the time? |
#8
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Mars colonization versus Stanford Torus
"Alex Terrell" :
The original proposal for PROFAC had a nuclear reactor and an ion engine. My idea is to have it suspended on tethers, which also supply electricity, so no need for the engine or the power plant. TANTAAFL - What do you think happens when a tether generates electric power? The tether's orbit starts to drop as the energy has to come from somewhere. No nuke or solar-cells for power means you are going to crash and darn soon too! Earl Colby Pottinger -- Cruising, building a Catamaran, Rebuilding Cabin, New Peroxide Still Design, Writting SF, Programming FOSS - What happened to the time? |
#9
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Mars colonization versus Stanford Torus
Earl Colby Pottinger wrote: "Alex Terrell" : The original proposal for PROFAC had a nuclear reactor and an ion engine. My idea is to have it suspended on tethers, which also supply electricity, so no need for the engine or the power plant. TANTAAFL - What do you think happen when a tether genarates electric power? The tether's orbit starts to drop as the energy has to come from somewhere. No nuke/solar for power means you are going to crash and darn soon too! Let me clarify. The tethers don't generate electric power. They supply power from a large mother ship in a 1000* km orbit. The mother ship has lots of power generation (might need to be nuclear as solar may not work too well at 1,000km), and electric propulsion. *Actually, a 400-500 km orbit would make the design easier. However, I would expect some rotovators to be around, and I think long cabled structures ought to be in the same orbit. |
#10
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Mars colonization versus Stanford Torus
Mike, can you write a short story based on this?
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