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#281
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Questions about "The High Frontier"
"Pat Flannery" wrote in message
... Still a significant amount of energy required per kilogram of material ending up in HEO. At some point it makes more sense just to shoot it up from Earth, or at least from the Moon. The energy per kilogram is exactly the point. One figure I know off the top of my head is that such energy costs from the moon to HEO are 1/20 the cost as from the Earth. And there are some NEAs where the delta-V is even lower than for the moon. The moon might compete with asteroids if the market is in HEO, and if the desired material is oxygen, silicon, iron, or aluminum. The Earth probably won't be able to compete for anything other than stuff like computer systems or certain kinds of precision (and low-mass) parts. The other problem is mining the asteroids per-say... solar flux at that distance is a lot lower than here on Earth, so a major source of free energy is not as effective. Making concentrating mirrors bigger ought to be easy in free fall. Having to double or triple your mirror area might not add that much to your total material costs since the mirror can be very flimsy. If you are going to try and colonize them, then it makes more sense just to leave the material right in the orbit it's in, and build your colonies out in the asteroid belt itself, rather than using all the energy to move it inwards toward Earth. Long-term, I'm sure you're right. But short-term the goal will not be colonization, it will be making a profit by serving an existing market. (The colonization will more or less happen as a consequence, not as the original goal.) So I think asteroidal material will be moved into Earth orbits because I think the initial enterprises will want to be close to the markets they serve, and at the onset that's going to be Earth. But then later on down the road, when commerce with Earth becomes the smaller part of the space economy, yeah, it makes lots of sense to build habitats in the Belt. Long-term, more may be built there than anywhere else. The Moon is a lot closer at hand for mining, you can walk and drive around on it, it has a lot more sunlight falling on it, and you have a reasonable transit time to and from Earth. The last argument is the strongest. One of the big problems of this scenario though is that it presumes that humanity will continue growing in numbers like yeast colonies and eventually run out of room on Earth to live. I would agree that, contrary to the expectations of some early 70's-era supporters, space habitats will not get built to relieve overcrowding on Earth. They will get built when we become serious about pursuing a destiny beyond the Earth. But that said, space habitats will permit the formation of a space-based civilization which may outgrow our planetary one by several orders of magnitude. or, in a different timeline, turn the bipedal apes into servants, with hilarious results somewhere down the line when they learn to speak, and begin to plot against us. :-) Heh. I was starting to flash on the current network TV sitcom "Cavemen" (Neanderthals coexist with modern Homo Sapiens, with hilarious results) before I saw where you were going with that. -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#282
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Questions about "The High Frontier"
On Oct 24, 12:32 pm, Pat Flannery wrote:
Hop David wrote: We're talking about payloads sent from an asteroid, not the entire asteroid. The former is much more plausible than the latter. Still a significant amount of energy required per kilogram of material ending up in HEO. At some point it makes more sense just to shoot it up from Earth, or at least from the Moon. The other problem is mining the asteroids per-say... solar flux at that distance is a lot lower than here on Earth, so a major source of free energy is not as effective. The other thing is that with there low gravity fields getting around on them is going to be more like EVAing than driving or walking. If you are going to try and colonize them, then it makes more sense just to leave the material right in the orbit it's in, and build your colonies out in the asteroid belt itself, rather than using all the energy to move it inwards toward Earth. The Moon is a lot closer at hand for mining, you can walk and drive around on it, it has a lot more sunlight falling on it, and you have a reasonable transit time to and from Earth. One of the big problems of this scenario though is that it presumes that humanity will continue growing in numbers like yeast colonies and eventually run out of room on Earth to live. There's no particular reason for that to be the case, as Spartan Condoms are cheaper than Space Colonies. Dropped to about 1/2 - 3/4 its present size by natural mortality and lowered birth rates over the next century if desired, there's no reason that the human population of Earth...particularly given new sources of renewable energy and recycling of materials... can't be quite happy and stable for the next few millenia. Population growth rates aren't controlled by the availability of birth control. In fact, nobody knows what determines population growth and decrease rates once the basic necessities of life are covered, they seem to follow a logic of their own. |
#283
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Questions about "The High Frontier"
Pat Flannery wrote:
Hop David wrote: We're talking about payloads sent from an asteroid, not the entire asteroid. The former is much more plausible than the latter. Still a significant amount of energy required per kilogram of material ending up in HEO. At some point it makes more sense just to shoot it up from Earth, or at least from the Moon. The earth is a steep gravity well with substantial atmospheric drag and gravity penalty. The moon has a shallower gravity well and no atmosphere. I believe the moon is the best source of oxidizer. Perhaps the lunar poles will provide other rocket fuel components and reaction mass, but I don't regard it as a given. If the moon is volatile poor then near earth asteroids, Phobos and Deimos could be the best source of hydrogen and hydrogen compounds. For various delta vee distances see http://clowder.net/hop/railroad/deltaveemap.html The other problem is mining the asteroids per-say... solar flux at that distance is a lot lower than here on Earth, so a major source of free energy is not as effective. We've been talking about NEOs, not main belt asteroids. Some NEOs get _more_ solar flux than earth. The other thing is that with there low gravity fields getting around on them is going to be more like EVAing than driving or walking. This is a good point. Learning how to get along with no gravity is a substantial obstacle. If you are going to try and colonize them, then it makes more sense just to leave the material right in the orbit it's in, and build your colonies out in the asteroid belt itself, rather than using all the energy to move it inwards toward Earth. Initially, I don't think they'd be colonized at all if they had no useful export to terrestial or near terrestial markets. The Moon is a lot closer at hand for mining, you can walk and drive around on it, it has a lot more sunlight falling on it, and you have a reasonable transit time to and from Earth. I got nothing against the moon. FWIW here's my current list of favorite low hanging fruit: 1) Moon 2) Phobos & Deimos 3) NEOs 4) Mars in that order. One of the big problems of this scenario though is that it presumes that humanity will continue growing in numbers like yeast colonies and eventually run out of room on Earth to live. I don't see space development as a way to deal with population growth but as a way to increase options. Of course, if we do settle NEOs and then the main belt, the population ceiling could increase by a factor of thousands. Hop |
#284
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Questions about "The High Frontier"
On Oct 23, 9:16 am, Hop David wrote:
While CCs may be poor in some those materials, there are other asteroids that aren't. I acknowledge that one asteroid containing all these resources would be rare. It would be hard for colonists on a metallic asteroid to use nitrogen from an NEO on a different orbit. On the other hand, there's no superhighways, oceans or rivers that can be used for transportation on Mars. Transportation will be a substantial barrier to self sufficiency on Mars as well as among the NEOs. But once an initial presence is established on Mars, i.e. a functioning town or other colony, constructing such (superhighways or the equivalent) is a relatively straightforward project, in comparison to establishing a viable interplanetary transport system between the asteroids. |
#285
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Questions about "The High Frontier"
Johnny1a wrote: Mike, you're a good guy and everything, but the above is a textbook example of thinking with your heart instead of your head. In any other context except space (you yourself bring up oil rigs) you would quickly recognize the absurdities. But since this is space we're talking about...well, things are different in space, right? Jim Davis- Hide quoted text - - Show quoted text - The only way any of that would make sense is if the cost of returning workers to Earth, and the related turnover, was less than the cost of constructing a habitat. Slot in selected assumptions about relative cost and you can reach an answer. The answer is almost surely going to be 'no'. What this all reminds me of is the Shuttle/ISS argument: "What can the Shuttle do, now that its military and commercial missions have been canceled?" "It can build a Space Station!" "What purpose will the Space Station serve?" "It will give the Shuttle something to build!" :-) Pat |
#286
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Questions about "The High Frontier"
Pat Flannery wrote:
What this all reminds me of is the Shuttle/ISS argument: "What can the Shuttle do, now that its military and commercial missions have been canceled?" "It can build a Space Station!" "What purpose will the Space Station serve?" "It will give the Shuttle something to build!" :-) Pat Except there's nothing in LEO. Ferdinand III of Castille would've been correct if he had pointed out there's nothing in the middle of the Atlantic Ocean worth the expense of building and sending carracks. Evidently Isabella didn't subscribe to that argument. Hop |
#287
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Questions about "The High Frontier"
Johnny1a wrote:
On Oct 23, 9:16 am, Hop David wrote: While CCs may be poor in some those materials, there are other asteroids that aren't. I acknowledge that one asteroid containing all these resources would be rare. It would be hard for colonists on a metallic asteroid to use nitrogen from an NEO on a different orbit. On the other hand, there's no superhighways, oceans or rivers that can be used for transportation on Mars. Transportation will be a substantial barrier to self sufficiency on Mars as well as among the NEOs. But once an initial presence is established on Mars, i.e. a functioning town or other colony, constructing such (superhighways or the equivalent) is a relatively straightforward project, in comparison to establishing a viable interplanetary transport system between the asteroids. Given backhoes, bulldozers & other heavy equipment, sure. Mars won't have the manufacturing infra structure to make a fleet of these any time soon. What finances sustaining and developing Martian settlements until they become self sufficient? I wouldn't rely on U.S. tax payers, political climate changes and leadership changes too frequently for the sustained prolonged effort that would be needed. Exports from the Moon, Phobos, Deimos and NEOs are a long shot, granted. But they're more plausible than exports from Mars. Hop |
#288
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Questions about "The High Frontier"
Johnny1a wrote: Population growth rates aren't controlled by the availability of birth control. In fact, nobody knows what determines population growth and decrease rates once the basic necessities of life are covered, they seem to follow a logic of their own. One problem they had with birth control in the third world (besides religious taboos, and macho issues) was that a lot of the people couldn't understand that the principle the condom worked on was (there's actually one culture I read about somewhere out there that recognizes no connection between sex and pregnancy. Women get pregnant when the gods deem they should get pregnant, and if a husband is away from his wife for a year and comes back to find her nursing a baby...well, that was just her time to get pregnant, that's all). :-) In one village in Africa, a family planning nurse demonstrated how the condom was to be used by putting it over the end of a broom handle; on her next visit, she noted that the villagers were now convinced that the birth rate was going to drop as every broom handle in the village now had a condom on it. Considering the number of unwanted pregnancies that occur here in the U.S. even nowadays, I suspect that easily available, reliable and low priced birth control worldwide would lead to a major decline in birthrate to below replacement levels, especially in non-sustenance agrarian societies - as that is one of the few areas where a large family is a asset, as many children means many workers to till the land. Even here in North Dakota average farm family size is far lower since the advent of advanced farm machinery, as back in the 1930's farm families with ten or more children were not uncommon. I even knew a farm girl born in the late 1950's who had eleven brothers and sisters. Pat |
#289
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Questions about "The High Frontier"
Johnny1a wrote:
On Oct 23, 5:58 pm, Jim Davis wrote: Mike, you're a good guy and everything, but the above is a textbook example of thinking with your heart instead of your head. In any other context except space (you yourself bring up oil rigs) you would quickly recognize the absurdities. But since this is space we're talking about...well, things are different in space, right? Jim Davis- Hide quoted text - - Show quoted text - The only way any of that would make sense is if the cost of returning workers to Earth, and the related turnover, was less than the cost of constructing a habitat. Slot in selected assumptions about relative cost and you can reach an answer. The answer is almost surely going to be 'no'. Slot in selected assumptions? You're leaving yourself wide open there. Bigelow Aerospace hopes to rent their habs at these rates: 4 weeks $15 million 8 weeks $18 million 1 year $88 million http://en.wikipedia.org/wiki/Bigelow_Aerospace A shuttle mission to carry workers would probably cost $450 million or more per round trip. http://www.nasa.gov/centers/kennedy/...uttle_faq.html These are just two selected assumptions from a multitude of possible scenarios. The Shuttle doesn't have to be the last word in transportation costs and there's a very wide spectrum of habs between Bigelow and O'Neill. Your conclusion that the answer is "almost surely going to be no" needs more back up before I accept it. Hop |
#290
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Questions about "The High Frontier"
Hop David wrote: "What can the Shuttle do, now that its military and commercial missions have been canceled?" "It can build a Space Station!" "What purpose will the Space Station serve?" "It will give the Shuttle something to build!" :-) Except there's nothing in LEO. Ferdinand III of Castille would've been correct if he had pointed out there's nothing in the middle of the Atlantic Ocean worth the expense of building and sending carracks. Evidently Isabella didn't subscribe to that argument. They didn't build anything for Columbus's voyage; all three ships already existed from Spain's already large merchant fleet doing business with the Indies, and they wanted a way there that was shorter and didn't have to deal with Muslim middleman for the spices and what-not they were getting from Asia. Even then the ships they gave Columbus were anything but top-notch, so they wouldn't be any great loss if they sailed off never to be seen again. It would have barely shown up on Spain's annual expenditures for 1492. Now, if you could do space exploration on a budget like that... say, grab a 1970's era 747, and a couple of fairly beat-up 1980's 737's and fly them to Mars or the asteroid belt, more power to you. Whereas colonization of North America panned out...though not for the Spanish in the long run...South America had too much jungle in its northern half, and Australia proved to be a huge wasteland that you could only inhabit the coastlines of. Yet either of those places were far, far, more amiable for habitation than the Moon, Mars, or the asteroids. As I pointed out before, you could start building cities in Antarctica in conditions more pleasant than Mars; you can breath the air, and water is already proven to be plentiful. There's bound to be minerals of one sort or another, transportation to and from the place is fairly quick and low cost, and assuming you like a diet high in meat rather than vegetables, the seas surrounding its coast will provide it in abundance. But you don't see cities springing up all over it or in the Australian outback (even Brazil pretty much admitted Brasilia was a flop of an idea), and that doesn't bode any too well for places that are even more uncomfortable in regards to climate. Say ones lacking breathable air and getting sprayed with the solar wind. Pat |
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