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#31
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Questions about "The High Frontier"
Johnny1a wrote: O'Neill's plan called for totally unrealistic space access by the standards of the 70s, he was assuming not only that the Space Shuttle would live up to NASA's hype, but that it would do _better_ over time, and he was assuming radically unrealistic constructions costs at every stage of the game, including assuming the availability of working models of technology that just hadn't been proven yet (and much of it still hasn't been.) He also assumed the development of huge reusable heavy lift boosters if the SPS constellation was to be built using Earth-launched materials, and if it ever is built, that's almost certainly the way it will be done, rather than going to all the trouble of building the Lunar infrastructure. What really makes me a critic, though, is not that O'Neill dreamed big, I admire that. The problem is that his dreams became so hyped that they actually became a negative force from a POV of space exploration and development. Critics used them as 'proof' that the entire concept of space exploration/exploitation was silliness, empty pipe dreams, while they raised supporters expectations to levels guaranteed to be disappointed. That probably had a lot to do with the enthusiasm shown by the aerospace industry for the concept; they full-well knew that the thing was wildly optimistic...but on the offhand chance it would get funded, they were willing to to play it up as a brilliant idea, because it would make the Apollo program look like a minor project by comparison. Pat |
#32
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Questions about "The High Frontier"
Jim Davis wrote: Why would just the athletes flee? Why not everyone else? Are only the athletes' lives in danger? Why aren't people fleeing now? They can't. Their lead content is so high that they've become immobile due to their mass. Even their pet dogs have been crushed flat under their own weight: http://tinyurl.com/cftp Pat ;-) |
#33
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Questions about "The High Frontier"
Johnny1a wrote: Population growth is a _good_ thing in the long term, survival-wise, population decrease is a sign of a declining society and even stablity is death in the long haul. Survival _requires_ growth and expansion, because sooner or later something unlikely in the short term but near- certain the long will do bad things to any given habitat. Population growth on Easter Island wasn't a good thing, nor in many areas where it led to soil depletion via overfarming to support a burgeoning population throughout human history. I did the math on this once, there were around 8.5 city blocks per person for everyone on the face of the planet, and that included using the seas as surface area also: that this is the total surface area of the Earth, not just the land masses: "Here's another way of looking at it; the total world population is around 6,490,115,551 as of this morning: http://www.census.gov/main/www/popclock.html The total surface area of the earth is 196,940,400 square miles: http://pages.prodigy.net/jhonig/bignum/qland2.html So if we take divide that population by that surface area we end up with an average of around 33 people per square mile of the Earth's surface. Now there are a total of 27,878,400 square feet in a mile, so we end up with one person for around every 844,800 square feet of the Earth's surface, or to put it another way, around one person for every 8.5 city blocks, which although they vary wildly in size tend to cover around 100,000 square feet total on average (assuming they are a tad over 300 feet on a side) Take the oceans out of that equation and you are starting to get near the point where we have only enough area to support our total population via farming, particularly when areas unsuitable for farming (mountains, forests, deserts) are taken into the equation. When you move out into space in any large numbers, the amount of area required for food production starts to look pretty daunting, particularly if you want a varied diet including things like meat and cheese, although I imagine a lot of things could be made in a synthetic form. Pat |
#34
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Questions about "The High Frontier"
The primary requirement for a space habitat is to provide a pressurized environment. That takes lots of tensile strength. Regolith has little or no tensile strength and even solid rock doesn't have enough. Even glass is much better, and steel and aluminum more so. So if we wind up building a steel or aluminum shell inside the asteroid to provide the pressurized environment, we have to ask what is the asteroid providing. Radiation protection? Fine, but we can get that with a shell no more than 6 feet thick. If we remove a certain amount of raw materials from the asteroid and refine it to glass, steel, and aluminum, the left-over slag is sufficient material for that 6 foot thick radiation shield. The concept I was thinking of is Niven's asteroid balloon. Take an iron asteroid, place water tanks at the centre, spin asteroid on its axis and bathe with concentrated sunlight from a solar mirror. Tank explodes, inflates molten steel asteroid into a large habitat. Most asteroids are just soft rubble piles anyway; they'd fly apart if you spun them any faster than once every 2 hours. Some sort of melting has to be done on the outer shell to stop one disintegrating; additionally, internal structural bracing such as steel cables are required to hold it together, especially if you want nice amenities like dirt and artificial gravity. O'Neill also mentioned spray-on space-based structures. That could do nicely for manufacturing large (100m) habitat modules. However, the Island One design is wildly extravagant - it would take many decades of settlement for habitats to become anything like comfortable. Yes, I'm entirely open to the idea that space habitats, instead of springing full-blown from a single project as O'Neill envisioned, might evolve as a series of incremental improvements to space hotels. We get to the 10th generation space Hilton, with its rotation for artificial G, its full radiation shielding, its closed ecology, and perhaps even use of natural sunlight, and people will suddenly go, "Hey, this is like that old Island One notion O'Neill was talking about back in the 20th Century". -- Regards, Mike Combs ---------------------------------------------------------------------- By all that you hold dear on this good Earth I bid you stand, Men of the West! Aragorn |
#35
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Questions about "The High Frontier"
Troy wrote:
The concept I was thinking of is Niven's asteroid balloon. Take an iron asteroid, place water tanks at the centre, spin asteroid on its axis and bathe with concentrated sunlight from a solar mirror. Tank explodes, inflates molten steel asteroid into a large habitat. Most asteroids are just soft rubble piles anyway; they'd fly apart if you spun them any faster than once every 2 hours. Some sort of melting has to be done on the outer shell to stop one disintegrating; additionally, internal structural bracing such as steel cables are required to hold it together, especially if you want nice amenities like dirt and artificial gravity. This has always struck me as implausible. It's hard to see how most, or even a few, nickel-iron asteroids would be uniform enough to make this work without just fracturing during the process, wrecking the whole enterprise. -- Erik Max Francis && && http://www.alcyone.com/max/ San Jose, CA, USA && 37 20 N 121 53 W && AIM, Y!M erikmaxfrancis Come not between the dragon and his wrath. -- Shakespeare, _King Lear_ |
#36
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Questions about "The High Frontier"
Jonathan skreiv:
There's a huge and glaring logical flaw with the idea of large scale colonies in space. If we can't learn how to sustain ourselves here on earth, with all the natural advantages and cheap resources. We have, infact, been sustaining ourselves here on earth for quite a while already thankyouverymuch. We've known how to do that trick since literally the first day a human ever walked the earth. If we hadn't, we'd be extinct by now. Infact we've done a lot more than merely "sustain" ourselves. We've spread and colonized every continent and just about every corner of every continent. There is no other large mammal that even comes close to being so widespread (I didn't say "numerous", though I suppose that may -also- be true if we count only animals with an adult mass above 50kg) Seems to me, by "sustain", you mean something different from sustain. Perhaps you mean that unless we can live with no influence on the world around us whatsoever, we're not "sustaining" ourselves. By that definition no species has ever been able to "sustain" itself anywhere. The true test of an enlightened civilization is to be able to sustain itself indefinitely. Not to simply find more room for unsustainable societies. Both makes sense. Everyone here agrees that it's /easier/ living on earth than elsewhere. But that's a bit like saying it's /easier/ living in Italy than in northern Scandinavia, so it makes no sense for anyone to be doing the latter. That is a strange kind of reasoning. Why do sci-fi writers assume we must move into space to survive??? Most don't. Eivind Kjørstad |
#37
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Questions about "The High Frontier"
"Erik Max Francis" wrote in message
t... Troy wrote: The concept I was thinking of is Niven's asteroid balloon. Take an iron asteroid, place water tanks at the centre, spin asteroid on its axis and bathe with concentrated sunlight from a solar mirror. Tank explodes, inflates molten steel asteroid into a large habitat. Most asteroids are just soft rubble piles anyway; they'd fly apart if you spun them any faster than once every 2 hours. Some sort of melting has to be done on the outer shell to stop one disintegrating; additionally, internal structural bracing such as steel cables are required to hold it together, especially if you want nice amenities like dirt and artificial gravity. This has always struck me as implausible. It's hard to see how most, or even a few, nickel-iron asteroids would be uniform enough to make this work without just fracturing during the process, wrecking the whole enterprise. There is another way to do an asteroid balloon that doesn't require the asteroid to be anywhere near uniform, nor for you to drill into it (although doing so would probably help). Put a balloon (mylar, perhaps) around the asteroid, and fill it with carbon monoxide. Get it warm and circulating. Then heat the balloon surface to deposit nickel and iron from carbonyl vapor. -l. ------------------------------------ My inbox is a sacred shrine, none shall enter that are not worthy. |
#38
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Questions about "The High Frontier"
On Tue, 02 Oct 2007 20:43:27 -0700, in a place far, far away, Johnny1a
made the phosphor on my monitor glow in such a way as to indicate that: On Oct 2, 12:51 pm, "Mike Combs" wrote: "Pat Flannery" wrote in message ... It was only after the book that every Tom, Dick, and Harry with a political or economic axe to grind began looking at space colonies as some sort of do-it-yourself Utopias where the innate superiority of their political or economic system would no doubt be shown to all. It might have been T. A. Heppenheimer who said, "Space colonies are a kind of political Rorschach test". But I am sanguine about space habitats as political experimentation laboratories. If one's society ultimately fails (or just consistently performs poorly), it would have to be a result of its underlying philosophy. In a space habitat, one could hardly blame resource depletion, an energy crisis, population pressures, a crop failure, or inconvenient location. Doesn't matter, 'cause it won't happen that way. When you consider the gargantuan capitol investments were talking about in building such machines, even once we're able to do so, the chances that they'll be given out to fringe movements or minority groups to 'experiment' with strains credulity. I know of no one who has proposed that they be "given out" to anyone. The "fringe movements" and "minority groups" will raise their own money to build them. |
#39
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Questions about "The High Frontier"
On Tue, 02 Oct 2007 23:21:20 -0500, in a place far, far away, Pat
Flannery made the phosphor on my monitor glow in such a way as to indicate that: But I am sanguine about space habitats as political experimentation laboratories. If one's society ultimately fails (or just consistently performs poorly), it would have to be a result of its underlying philosophy. In a space habitat, one could hardly blame resource depletion, an energy crisis, population pressures, a crop failure, or inconvenient location. How about if a neighboring colony blows a hole in yours to let the air out, then seizes it for their own, as they want to increase their population? The hole would be repaired long before the air went out. A hole big enough to cause a total evacuation of the colony faster than it could be fixed would be so big as to wreck the colony. If colonies are affordable for "fringe groups," they're probably sufficiently cheap that it makes more sense to build another one for expansion than making war and stealing someone else's. It's not like rare prime real estate. A more likely cause of war would be ideological hatred. A Hamas space colony would still plot ways to destroy the Jew space colony. |
#40
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Questions about "The High Frontier"
On Wed, 3 Oct 2007 06:03:40 +0200 (CEST), in a place far, far away,
Jim Davis made the phosphor on my monitor glow in such a way as to indicate that: Jonathan wrote: I think the upcoming Olympics in Beijing will provide a glimpse into the priorities of the future. China burns so much coal that it's air is almost deadly. Dear Mother Nature will give us a few very calm days in Beijing so the world can watch the athletes flee the city for their very lives. Why would just the athletes flee? Why not everyone else? Are only the athletes' lives in danger? Why aren't people fleeing now? Don't confuse jonathan with logic. |
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