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#291
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Questions about "The High Frontier"
Hop David wrote: 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 And we hoped to launch payloads on the Shuttle at around $118.00 per pound. When Bigelow gets a habitat in orbit and people start renting it, then we'll see what the price is, and how many customers are lining up. Pat |
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Questions about "The High Frontier"
On Oct 23, 12:02 pm, "Mike Combs"
wrote: There seems to be an assumption that overland travel on Mars has got to be easier than moving between asteroids because the latter is space travel and the former isn't, and as everybody knows, space travel is difficult, dangerous, and hideously expensive. I think this notion overlooks two points: 1. Overland travel on Mars, unlike same on Earth, will have pressurization and other life-support requirements little different from space travel. 2. Our notions of space travel are influenced by our most common experience of it, which is to say, travel from the surface of the Earth into orbit. Such travel requires large amounts of thrust (greatly in excess of vehicle weight in 1-G) quickly achieved, and an aerodynamic shape. None of these will be requirements for systems traveling from one asteroid to another. These are legitimate points. If one is _in_ space, one doesn't need an awful lot of thrust to go places. However, while a Mars buggy needs to be pressurized, a voyage from one asteroid to another, if it is to have modest fuel requirements, will take a while. Trips between the Kuiper Belt for biomass and the Asteroid Belt for metals will take many years. So, while you are right that the commonplace view based on past experience of an Apollo moon mission versus a drive to the country in one's car exaggerates the situation, Mars is a single body that has both metals and carbon, hydrogen, oxygen, and nitrogen available. So I think it is still favored for lower start-up costs despite the fact that the disparity can be exaggerated. John Savard |
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Questions about "The High Frontier"
Pat Flannery wrote:
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; You're ignoring some of my points. There's nothing in LEO. Just as, from Ferdinand III's point of view, there was nothing in the middle of the Atlantic. There were no Carracks in the time of Ferdinand III. And the resources of the mid-Atlantic would not have justified the development and building of Carracks. Again, pointing out that LEO is a dead end is not an argument that we shouldn't bother to build our spacefaring capabilities. 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. I've mentioned Mars and the asteroid belt as possibilities only after other intermediate steps are accomplished. Skipping these steps would be like sending the Santa Maria straight to Sutter's Mill. And on his first voyage, Columbus did little more than bring back information. It was more comparable to the Clementime Mission and other Discovery missions around our neighborhood in the solar system. 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. http://www.globalwarmingart.com/imag...from_Space.jpg I can see the growing corridor between Tucson and Phoenix near where I live. These cities are expanding and fusing into a single huge megapolis. Driving to Phoenix, I can see many formerly uninhabited regions that are now row after row of houses. Who's to say what this picture will look like 100 years from now? And again, I don't see space development as an escape valve for mounting population pressures. I see it as a way to increase options. Hop |
#294
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Questions about "The High Frontier"
Quadibloc wrote:
On Oct 23, 12:02 pm, "Mike Combs" wrote: There seems to be an assumption that overland travel on Mars has got to be easier than moving between asteroids because the latter is space travel and the former isn't, and as everybody knows, space travel is difficult, dangerous, and hideously expensive. I think this notion overlooks two points: 1. Overland travel on Mars, unlike same on Earth, will have pressurization and other life-support requirements little different from space travel. 2. Our notions of space travel are influenced by our most common experience of it, which is to say, travel from the surface of the Earth into orbit. Such travel requires large amounts of thrust (greatly in excess of vehicle weight in 1-G) quickly achieved, and an aerodynamic shape. None of these will be requirements for systems traveling from one asteroid to another. These are legitimate points. If one is _in_ space, one doesn't need an awful lot of thrust to go places. However, while a Mars buggy needs to be pressurized, a voyage from one asteroid to another, if it is to have modest fuel requirements, will take a while. Trips between the Kuiper Belt for biomass and the Asteroid Belt for metals will take many years. Trips to the Kuiper belt for biomass are unnecessary, in my opinion. http://clowder.net/hop/railroad/asteroidresources.html Nor are trips to the asteroid belt. I suspect both metallic asteroids and asteroids with ice interiors exist among the NEOs. So, while you are right that the commonplace view based on past experience of an Apollo moon mission versus a drive to the country in one's car exaggerates the situation, Mars is a single body that has both metals and carbon, hydrogen, oxygen, and nitrogen available. So I think it is still favored for lower start-up costs despite the fact that the disparity can be exaggerated. And what would the return on investment for martian start up costs be? I can imagine profitable exports from the Moon, Phobos, Deimos or NEOs to near earth space. These may be unlikely but profitable Martian exports are far more unlikely. Hop |
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Questions about "The High Frontier"
In rec.arts.sf.science Pat Flannery wrote:
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). :-) These perceptions can be changed in time, though. A perhaps greater problem is that children are the only form of social security and retirement planning that exists in many countries, and these countries tend to have high child mortality rates as well. If you want to be highly confident of having enough children around to take care of you when you're old and your children have a fair chance of dying first, you need to have a *lot* of them. And of course most of the time most of them live and you have a lot more than needed. Hence, population explosion. In first world countries you can be very comfortable in your old age with no children at all with good retirement planning, and if there's a good social security system you don't even need that, so the number of children you need to have to ensure a comfortable old age drops to zero. There's a looming crisis now in the first world countries in the form of the rapidly aging population and the rapidly increasing health care costs which go with it. This will no doubt be manageable, but largely because the first world countries have lots of economic output with which to manage it. Foisting this problem on poor countries without first addressing the problem of them being poor seems like putting the cart before the horse to me. -- Michael Ash Rogue Amoeba Software |
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Questions about "The High Frontier"
Pat Flannery wrote:
Hop David wrote: 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 And we hoped to launch payloads on the Shuttle at around $118.00 per pound. When Bigelow gets a habitat in orbit and people start renting it, then we'll see what the price is, and how many customers are lining up. Pat You snipped a lot of context. I was arguing against the notion that worker transportation costs would surely not justify hab construction. Even given more pessimistic hab costs and more optimistic transportation costs (the website you snipped said $450 million per shuttle trip), transportation expense could justify construction of habs. Hop |
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Questions about "The High Frontier"
Hop David wrote: There were no Carracks in the time of Ferdinand III. And the resources of the mid-Atlantic would not have justified the development and building of Carracks. As to carracks, there were indeed carracks around in the 15th century... in fact, I hate to do this... but the Santa Maria was a carrack: http://en.wikipedia.org/wiki/Carrack http://en.wikipedia.org/wiki/Santa_M...ADa_%28ship%29 http://www.globalwarmingart.com/imag...from_Space.jpg I can see the growing corridor between Tucson and Phoenix near where I live. These cities are expanding and fusing into a single huge megapolis. Driving to Phoenix, I can see many formerly uninhabited regions that are now row after row of houses. Who's to say what this picture will look like 100 years from now? So we build a highway and rail link to the Moon and Mars? That's been suggested befo http://www.vanishingbooks.com/featur...omearthfxd.jpg Pat |
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Questions about "The High Frontier"
On Mon, 22 Oct 2007 13:09:20 -0500, "Mike Combs"
wrote: "Bryan Derksen" wrote in message news:E8SSi.105062$th2.51759@pd7urf3no... Seems like a lot of extra expense moving an entire asteroid to L5 before mining volatiles out of it when one could mine the volatiles on-site and ship just those back. Then there's one idea that I like: If you're using a mass-driver as your reaction engine, the beauty of it is that you can use literally anything for reaction mass. So maybe you start materials processing on the way home, and use the dross for reaction mass. Then by the time you get home, what's left is the high-dollar materials. You know, for someone who just one post ago was proclaiming how energy was and always will be the dominant factor in space operations, you're awfully free with the gigawatts here. Because even a measly hundred-meter asteroid, delivered to L5 using the mass-driver approach you describe, is going to require a gigawatt or so of continuous electric power for several years. No doubt you are going to just wave your hands and say, "in space, sunlight is free!". Solar power generation equipment is *not* free, and I'm pretty sure that whoever winds up actually paying the bills, is just going to go and bring back whatever asteroidal materials they actually need, when they need them. Not entire asteroids, just becacuse it would be nifty to have one close at hand. -- *John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * * for success" * *661-951-9107 or 661-275-6795 * -58th Rule of Acquisition * |
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Questions about "The High Frontier"
On Tue, 23 Oct 2007 08:26:08 -0700, Hop David wrote:
Michael Turner wrote: I don't think hysteria is the right word. Large payloads would be harder to control and a tiny error could change aerobraking to lithobraking. I would call it "Deep Impact sensible fear". Again, I advocate payload mass ceilings well below Tunguska size. I'm still curious whether there might be a way to increase payload mass and reduce terrestrial hazards by delivering asteroid-derived payloads to Earth orbit in the form of large spherical shells of material. As I've probably mentioned in this forum before, I was once asked to look at an RFP for "demisable tanks" -- i.e., satellite fuel tanks guaranteed to burn up on reentry. That inquiry went nowhere, AFAIK. Which underscores a point: maybe you don't need ablative shielding or heat-soaking tiles to bring stuff down intact. After all, LEO satellite fuel tanks have been found in desert regions with little more than scorch marks and dents from hitting the ground (at a relatively low terminal velocity, obviously.) Maybe that's a bug for satellite fuel tanks, but it's arguably a feature if you're interested in aerobraking or aerocapture of resources delivered from cislunar or interplanetary space. Now let's say you want to deliver a lot of asteroid-mined metal to an L-point, using aerobraking in the Earth's atmosphere. Blow the metal up into a big, relatively thin-walled sphere. Maybe store some asteroid-derived volatiles inside, which would coat the interior as they freeze down to the point where you get into equilibrium with sublimation losses. Asteroid mined metal would come from a metallic asteroid which is unlikely to have volatiles. Actually, the stony chondrites are typically 10% metal or so, and metal in a much more easily recovered form - the stuff can be magnetically seperated from finely crushed rock, and there's reason to believe that lots of stony chondrites have pre-crushed surfaces. If not, well, we know how to make rock-crushers. Metal asteroids, seem to be solid metal. Solid nickel steel, rather like the stuff battleships used to be made out of. This poses certain obvious problems for any wannabe asteroid-miner... -- *John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * * for success" * *661-951-9107 or 661-275-6795 * -58th Rule of Acquisition * |
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Questions about "The High Frontier"
On Mon, 22 Oct 2007 12:56:53 -0500, "Mike Combs"
wrote: "John Schilling" wrote in message .. . OK, let's see: How about useful concentrations of Helium, Lithium, Beryllium, Boron, Nitrogen, Fluorine, Neon, Sodium, Aluminum, Chlorine, Argon, Potassium, Titanium, Chromium, Manganese, Copper, Zinc, Arsenic, Bromine, Krypton, Strontium, Zirconium, Niobium, Molybdenum, Silver, Tin, Antimony, Iodine, Xenon, Barium, Hafnium, Tantalum, Tungsten, Gold, Mercury, Lead, Bismuth, Thorium, and Uranium. You may have a point here, although I would venture to say that we use minor quantities of these materials in comparison to steel, glass, and concrete. Perhaps asteroidal settlements will buy aluminum and titanium from lunar colonies, who in turn will be interested in buying hydrogen, carbon, and nitrogen from asteroid settlements. What sort of asteroid were you imagining had useful concentrations of Nitrogen, again? And the Moon seems scarcely better, though it's at least different and it's big enough that there's still room for surprises. Mostly, though, both the Moon and the Asteroids are very boring, geologically speaking, each rich in about half a dozen or so sorts of useful stuff and that's about it. For the full range of minerals you need to support a civilization, you really want something with a more interesting geology. Making them useful requires more than just keeping them spinning, as you ought to know by now. Yes, but the question we were dealing with was what is the extra expense of having to provide your own gravity. So it's a valid point. If all you want is gravity, you don't need to fly to an asteroid. If what you want is gravity in a location that's conveniently placed to whatever unique advantages the asteroid environment offers, you need to not only *have* gravity, but you need a convenient way to get from where the gravity is to where the asteroid is. Unless your goal is to just watch the asteroid spin by your window every minute or so, which seems pointless. Otherwise, making something spin is the easy part. The interface between the spinning part and the rest of the universe, is where it gets hard. But the premise is false, because real-world economics are a whole lot more complicated than that. Energy is rarely the dominant consideration. It's currently the dominant consideration in space, and is likely to remain so for the foreseeable future. Energy is the dominant consideration in space? Why is it that my copy of Larson & Wertz's "Space Mission Analysis and Design", devotes only seventy-one of its nine hundred seventy pages, to the chapters on power and propulsion systems? Why is it that in ten years of work as a professional space mission analyst, I have *never* had a customer say, "My spacecraft would work best if it were in Orbit X, but it would take lots of energy to get there so I'll settle for more accessible Orbit Y instead"? Heck, why have none of them ever even said, "Hey, interesting idea, I'll have to think about that" when I suggested Orbit Y myself? Energy has *never* been the dominant consideration in space. At least, not if you're talking about people who actually do stuff with actual spacecraft. Imaginary spacecraft are a different matter, obviously. -- *John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * * for success" * *661-951-9107 or 661-275-6795 * -58th Rule of Acquisition * |
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