|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Technologies for Moon mission useable for missions further out
It isn't quite obvious to me that it would be better to grow crops in cav es than in greenhouses on the surface. I would expect something like a greenhouse with 10 kP atmospheric pressure, 85% O 2 and 15% CO2 to be workable. You would need a relatively large volume to grow all the food for a crew. I think you're laboring under the assumption that I'm proposing the kind of caves that people would need to stoop to walk into. I'm not. I'm talking about lava tubes on the Moon and Mars. Have you heard about those? (I already supplied a link above.) "A 1969 paper by Oberbeck, Quaide, and Greeley, taking into account only the Moon's lighter gravity, and not the stronger nature of lunar anhydrous glass,[1] calculated lunar lavatubes could reach 340 meters in span (lengths could go to kilometers).[2] There are some indications in Coombs and Hawke's work (see "Locations" below) that some lavatubes may be much larger." http://www.lunarpedia.org/index.php?title=Lava_Tubes And now we have some data: The lunar lava tube skylight discovered by some Japanese researchers hole might be almost 400 meters wide at the point of the skylight. http://www.planetary.org/blog/article/00002173/ On Mars, with about twice lunar gravity, lava tubes will be smaller. But the big ones will still be enormous by terrestrial standards. More than enough volume, if volume is what you're worried about it. What you should really be worried about with a surface greenhouse: - wind storms creating structural loads (more mass to take to Mars) - dust abrasion at the greenhouse's interfaces to the atmosphere (mechanical wear on air pumps needed to keep it pressurized; filters clogging up) - *toxic dust* - http://www.usatoday.com/tech/science/space/2006-08-01-m ars-storms_x.htm - very low surface temperatures at night (during which you *will* need to supply heat just to keep the plants from freezing, as the dome radiates heat away), - UV degradation of the greenhouse skin - maybe plant pathology issues, under occasional solar storms. In short, pretty much the same problems you'd be dealing with if you had a sky-exposed greenhouse on the Moon, with some things harder (wind-blown toxic dust, for example) on Mars, and some things easier (e.g., where to get your initial CO2.) I'd bet what would end up working best for both the Moon and Mars is to concentrate sunlight on the surface and pipe it down into a shelter set up on the floor of a lava tube. For crops requiring more frequent light, you might want artificial sources during the long Martian night. Even if Martian agriculture could be done robotically, people on Mars might prefer being more hands-on about their food sources. After all, they'll be in stuck in a very artificial and limited environment much of the time; and even where it's natural, it will be starkly desert- like, very alien and rather dangerous. Growing crookneck squash and your own fresh basil -- maybe raising chickens, too, and if you can find/make/take enough water, would fish-farming be too much to ask for? .... Well, farming might be just the thing to take your mind off how far you are from home, how hostile the external environment is, and how many unforeseen variables have popped up in the question of whether you'll ever be able to get back. I think food production (and at the same time O2 production from CO2) is one of the most important (if not the most important) technology to be developped for space exploration. It is right up there with cheap access to space. I wouldn't say so. We have some idea of how to do closed-cycle long- term human life support. Cheap access to space is a much harder problem. Moreover, if access to space became _very_ cheap somehow, would allow you to defer the whole problem of extraterrestrial food production indefinitely. The really big question is, I think, psychological: will people really want to live in space, or just visit? A sustainable human future might depend on large-scale exploitation of space resources (and on space as the ultimate industrial effluent sink, the other part of the equation Gerard O'Neill wanted to address). But even if so, it doesn't necessarily depend on human presence. -michael turner On Jun 15, 11:13 am, Alain Fournier wrote: Michael Turner wrote: You're basically compensating for a lot of environmental differences just to get one thing: sunlight passing through directly to plant leaves. Is this really more sensible than piping sunlight from a concentrator on the surface to a more controllable environment below the Martian surface? To live economically on the Moon for extended periods, you'll have to develop some way to grow food in caves. To go to Mars, you'll (probably) have to develop technologies for growing food aboard ship -- not too different from growing it in caves. To live on Mars, you'll have to live underground most of the time -- like you did on the Moon. Water from the atmosphere? Water vapor content is about 0.0 3% - of a very thin atmosphere. You're more likely to find acceptably high concentrations somewhere else -- say, underground? It isn't quite obvious to me that it would be better to grow crops in cav es than in greenhouses on the surface. I would expect something like a greenhouse with 10 kP atmospheric pressure, 85% O 2 and 15% CO2 to be workable. You would need a relatively large volume to grow all the food for a crew. And space pressu rized at 101 kP wouldn't be cheap. So it might be easier to build a low pressure greenhouse exposed to sunlight than to grow the food in a more Earthly atmospheric environment with artificial light. I'm not saying one method is superior to the other. I'm saying that it isn't obvious to me which is best. Tending to the crop at 10 kP means farming in a pres sure suit, so it isn't obvious that it is easy. But, I would expect most of the work to be automated, and once the basic installation is setup, it should be in many regards easier than farming on Earth because you don't expect weeds to be much of a problem nor would the weather be a problem. I'm also saying, that if you build a lunar base, the money you invest fig uring out which is the best method of crop production, is not money spent solely for the lunar base. It is also mone y spent preparing martian and/or asteroidal exploration as the technology is probably easily adaptable. So devellopin g food production on a lunar base might be more important than extracting water from the probable polar ice deposits. I think food production (and at the same time O2 production from CO2) is one of the most important (if not the most important) technology to be developped for space exploration. It is right up there with cheap access to space. Alain Fournier |
#12
|
|||
|
|||
Technologies for Moon mission useable for missions further out
In sci.space.tech message ,
Mon, 14 Jun 2010 22:13:37, Alain Fournier posted: It isn't quite obvious to me that it would be better to grow crops in caves than in greenhouses on the surface. I would expect something like a greenhouse with 10 kP atmospheric pressure, 85% O2 and 15% CO2 to be workable. You would need a relatively large volume to grow all the food for a crew. And space pressurized at 101 kP wouldn't be cheap. So it might be easier to build a low pressure greenhouse exposed to sunlight than to grow the food in a more Earthly atmospheric environment with artificial light. I'm not saying one method is superior to the other. I'm saying that it isn't obvious to me which is best. Tending to the crop at 10 kP means farming in a pressure suit, so it isn't obvious that it is easy. Aside: You mean 10 kPa. P is for poise. Perhaps not. On Earth, we generally have large quantities of soil found just lying about the place. Off Earth, soil will be in limited supply and valuable. It can well be that it will be kept in trays of modest size, such that a farmer can reach the middle without actually standing on the stuff. With "farmland" on trays standing on blocks or tables or with legs, with aisles between the trays, the robots can easily bring the trays in turn into a reasonably Earthly atmosphere for planting weeding thinning and harvesting. It need not be at 100 kPa; the farmers can wear lightweight non-pressure suits to hold a somewhat enriched breathing atmosphere. -- (c) John Stockton, near London. Web URL:http://www.merlyn.demon.co.uk/ - FAQish topics, acronyms, & links. Correct = 4-line sig. separator as above, a line precisely "-- " (RFC5536/7) Do not Mail News to me. Before a reply, quote with "" or " " (RFC5536/7) |
#13
|
|||
|
|||
Technologies for Moon mission useable for missions further out
Michael Turner wrote:
I think you're laboring under the assumption that I'm proposing the kind of caves that people would need to stoop to walk into. I'm not. I'm talking about lava tubes on the Moon and Mars. Have you heard about those? (I already supplied a link above.) "A 1969 paper by Oberbeck, Quaide, and Greeley, taking into account only the Moon's lighter gravity, and not the stronger nature of lunar anhydrous glass,[1] calculated lunar lavatubes could reach 340 meters in span (lengths could go to kilometers).[2] There are some indications in Coombs and Hawke's work (see "Locations" below) that some lavatubes may be much larger." I'm not sure exactly how one would pressurize such lava tubes. It isn't easy to put 340 m span wall with a 100 kPa difference in pressure between the inside and the outside. I would think that at first, colonist would build more modest modules, maybe located inside lava tubes for radiation and meteorite shelter. But longer term, using the entire volume of the lava tube is a very interesting prospect. But then again, longer term, you will probably have much a bigger population and you might want to use the entire lava tube for human occupation and let the farming be done in greenhouse on the ground. http://www.lunarpedia.org/index.php?title=va_Tubes And now we have some data: The lunar lava tube skylight discovered by some Japanese researchers hole might be almost 400 meters wide at the point of the skylight. http://www.planetary.org/blog/article/00002173/ On Mars, with about twice lunar gravity, lava tubes will be smaller. But the big ones will still be enormous by terrestrial standards. More than enough volume, if volume is what you're worried about it. What you should really be worried about with a surface greenhouse: - wind storms creating structural loads (more mass to take to Mars) - dust abrasion at the greenhouse's interfaces to the atmosphere (mechanical wear on air pumps needed to keep it pressurized; filters clogging up) - *toxic dust* - http://www.usatoday.com/tech/science/space/2006-08-01-m ars-storms_x.htm - very low surface temperatures at night (during which you *will* need to supply heat just to keep the plants from freezing, as the dome radiates heat away), - UV degradation of the greenhouse skin I think we can solve the technical issues above, it might not be as easy as it looks, but we have built lots of stuff that can operate in harsh environments. I see no reason why the above would be impossible to solve. I don't know if it would turn out to be cheaper than to do the farming in the underground module with an Earthly controlled atmosphere, but we can solve the above issues. - maybe plant pathology issues, under occasional solar storms. Yes, that and can plants grow in a gravity field much less than 1 g? Until we try to do it, we should assume that farming off Earth can have unexpected difficulties. Even if Martian agriculture could be done robotically, people on Mars might prefer being more hands-on about their food sources. After all, they'll be in stuck in a very artificial and limited environment much of the time; and even where it's natural, it will be starkly desert- like, very alien and rather dangerous. Growing crookneck squash and your own fresh basil -- maybe raising chickens, too, and if you can find/make/take enough water, would fish-farming be too much to ask for? .... Well, farming might be just the thing to take your mind off how far you are from home, how hostile the external environment is, and how many unforeseen variables have popped up in the question of whether you'll ever be able to get back. Not for me, I can't keep plants alive. But yes for some people that could be a good way of keeping their sanity in such a far out place. Alain Fournier |
#14
|
|||
|
|||
Technologies for Moon mission useable for missions further out
Dr J R Stockton wrote:
Mon, 14 Jun 2010 22:13:37, Alain Fournier posted: It isn't quite obvious to me that it would be better to grow crops in caves than in greenhouses on the surface. I would expect something like a greenhouse with 10 kP atmospheric pressure, 85% O2 and 15% CO2 to be workable. You would need a relatively large volume to grow all the food for a crew. And space pressurized at 101 kP wouldn't be cheap. So it might be easier to build a low pressure greenhouse exposed to sunlight than to grow the food in a more Earthly atmospheric environment with artificial light. I'm not saying one method is superior to the other. I'm saying that it isn't obvious to me which is best. Tending to the crop at 10 kP means farming in a pressure suit, so it isn't obvious that it is easy. Aside: You mean 10 kPa. P is for poise. Yes that is obviously what I meant. Thanks for the correction. Perhaps not. On Earth, we generally have large quantities of soil found just lying about the place. Off Earth, soil will be in limited supply and valuable. It can well be that it will be kept in trays of modest size, such that a farmer can reach the middle without actually standing on the stuff. Someone last year grew some plant in a Moon regolith imitation. It isn't the most fertile soil but you can grow stuff in it. You then compost the plants that grew in the regolith to have a fertile ground for farming. So at first fertile soil would be in limited supply, but with time you can make as much as you want. With "farmland" on trays standing on blocks or tables or with legs, with aisles between the trays, the robots can easily bring the trays in turn into a reasonably Earthly atmosphere for planting weeding thinning and harvesting. It need not be at 100 kPa; the farmers can wear lightweight non-pressure suits to hold a somewhat enriched breathing atmosphere. Interesting. I hadn't thought about that. Alain Fournier |
#15
|
|||
|
|||
Technologies for Moon mission useable for missions further out
On Jun 18, 12:14 pm, Alain Fournier wrote:
"I'm not sure exactly how one would pressurize such lava tubes." I have not proposed pressurizing lava tubes. I was addressing an apparent concern of yours: whether they had enough volume for agriculture. I was merely pointing out that the size of some lunar lava tubes dwarfs that of any structures (including greenhouses) currently envisioned for formal Mars missions. The main point of these lava tubes would be to have a roof over your head that shields you (and your crops) from CGR, solar storms, dust and temperature extremes. What you build *inside* them doesn't have to be proof against those threats -- meaning less mass to take along to Mars, less time spent in construction of habitats, less maintenance complexity, more safety in what's otherwise a hostile environment not too different from that of the Moon. I don't propose lava tubes as a *substitute* for artificial habitats or greenhouse, even if they have some speculative potential for that in colonization scenarios. Remember, the topic here is "technologies for Moon mission usable for missions further out". "... But longer term, using the entire volume of the lava tube is a very interesting prospect. But then again, longer term, you will probably have much a bigger population and you might want to use the entire lava tube for human occupation and let the farming be done in greenhouse on the ground." When would that be? When Mars has a population of millions? Humoring you, for the moment: Look at intermediate stages of economic development. You seem to be assuming that every inhabited lava tube must grow its own food. Well, how French of you! ;-) Why can't some lava tubes become more specialized for food production, others for habitation, if the initial tube gets too crowded for farming? There will be no shortage of lava tubes for the time being. There are major industrialized nations on Earth that get by fine without 100% food self-sufficiency. I live in densely-populated Japan. My kiwi fruit comes in from sparsely-populated New Zealand. Even my "Made in Japan" tofu is mostly soy from the sparsely-populated United States. I don't buy Japanese wine made from Japanese grapes, because it's wretchedly awful -- but I do have two bottles of Australian shiraz at the moment. So if I lived in a lava tube on Mars, why would I buy my own tube's food, if I could get it cheaper (or better) by importing from other lava tubes? Or for that matter, if I could get it shipped down to me from Phobos Farms (TM)? After all, might be some delicacies that can only be grown in weightlessness, for all we know. If Mars starts out a one-tube settlement, and the population grows to the point where living space is in competition with agricultural space, eventually somebody will figure out there's a business opportunity in the higher food prices inevitably resulting. The cost of space in a neighboring lava tube might be near zero, and the capital costs of developing that new tube for agriculture, plus the continuing cost of transporting food back to the old tube, might still be cheaper than farm-space rent in the old tube. At that "tipping point", the old tube's farm-spaces turn rapidly toward residential and commercial uses, the new tube becomes mostly farm-space. It's a story that's played out for literally thousands of years in terrestrial economies. Yes, even in France, not so many centuries ago. It's a story that might play out on the Moon before anybody even gets to Mars. It's hard to see why the economics of agricultural vs. residential land use would change dramatically just because you're no longer on Earth. In any case, I thought we were talking about lunar mission technology reusable for Mars missions, in the foreseeable future, not about colonization. I think we can solve the technical issues above, it might not be as easy as it looks, but we have built lots of stuff that can operate in harsh environments. I see no reason why the above[list of problems with surface greenhousese] would be impossible to solve. Engineering is not about what's possible. Lots of things are possible. But what gets done? The things that are feasible. If agricultural equipment engineered for lunar lava tubes ends up over- engineered in some ways for Mars, at least it's already been engineered. It might require only slight adaptation for Mars. That reduces mission development costs and gives you a margin of safety, with proven equipment, upon arrival. Setting up agriculture on Mars would take time, during which you might be relying on food drops from the mothership's closed-cycle (no longer!) garden operations in Mars orbit. Afterward, if some mission staff happen to have some time to spare and can afford to take the risks involved, they might *experiment* with growing stuff in greenhouses on the surface of Mars, on a small scale, to see if it might be made *feasible* for future missions. However, even if it turns out to be possible, it will probably be inferior to growing food in lava tubes in terms of what matters: price/performance. What you end up using to grow food will probably be more like what you used on the ship that brought you, in an environment more like the ship's. Remember: even Martian "dirt" might not be free: you might have to detoxify it. If what you're talking about is colonization, that's a different topic, and a future none of us is likely to see. I thought the topic was "technologies for Moon mission useable for missions further out". But even in the colonization scenario: if I lived on Mars, I wouldn't buy food from surface farms if I could get the same quality at a better price from farms hosted more cheaply in lava tubes. So even if the surface greenhouse problem is solvable *technically*, such greenhouses will end up being only scientific curiosities if they can't produce food more *economically*. To repeat: greenhouses on the Martian surface will get exactly one benefit from being on the surface: direct daytime pass-through of sunlight at frequencies useful for photosynthesis. That's IT. Everything else about being on the surface is just a source of added problems. Solving problems costs money. Money that nobody will pay if there are cheaper solutions that are just as good. If some multi-billionaire just HAS to see a beautiful dome with greenery in it, sparkling under the Martian sky, before he dies, to fulfill his SF-illustration-fired boyhood dreams of what a Mars base was *supposed* to look like, with cost no object, well ... then maybe it'll happen. Where costs matter, it probably won't. Stuff in space never ends up looking like the "artist's rendition". It always looks like it was custom-engineered for a highly unusual environment by the lowest bidder. Funny how that works, eh? Throw out the SF illustrations. Throw out your old intuitions. On Earth, the only agricultural product grown in caves is the truffle, an expensive delicacy. On Mars, maybe tequila will be the drink of choice for those who feel compelled to consume conspicuously, but only if it's distilled from those expensive *surface-grown* greenhouse cacti, with a bottle costing a month's average pay packet. Connoisseurs will claim to be able to tell the difference. Blind taste-testing will reveal that they are deceiving themselves, but they will be undeterred. -michael turner |
#16
|
|||
|
|||
Technologies for Moon mission useable for missions further out
At Thu, 17 Jun 2010 23:15:06 EDT Alain Fournier wrote:
Someone last year grew some plant in a Moon regolith imitation. It isn't the most fertile soil but you can grow stuff in it. You then compost the plants that grew in the regolith to have a fertile ground for farming. So at first fertile soil would be in limited supply, but with time you can make as much as you want. Organic waste = soil. This is pretty much where 'fertile' soil on the earth came from originally. Yes, it takes time. Any colony on the Moon or Mars will have to deal with various sorts of organic waste somehow. Composting it into soil is probably the best solution. -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software -- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database -- Contract Programming: C/C++, Tcl/Tk |
#17
|
|||
|
|||
Technologies for Moon mission useable for missions further out
Michael Turner wrote:
On Jun 18, 12:14 pm, Alain Fournier wrote: "I'm not sure exactly how one would pressurize such lava tubes." I have not proposed pressurizing lava tubes. I was addressing an apparent concern of yours: whether they had enough volume for agriculture. Well, yes at first you do have enough volume in the lava tubes for agriculture. But I think, I'm not sure, that agriculture would be done in a volume which is bigger than the habitat, and that it would be cheaper to make this volume a lower pressure compartment than the habitat. Therefore, the farming module and the habitat module would be quite different from one another. So as you said below, there is no reason to make it directly part of the habitat it can be separated. If the plants need protection from radiation then, making this agriculture module also in the lava tube makes sense. If the plants can use direct sunlight, I would think that doing so would be cheaper. "... But longer term, using the entire volume of the lava tube is a very interesting prospect. But then again, longer term, you will probably have much a bigger population and you might want to use the entire lava tube for human occupation and let the farming be done in greenhouse on the ground." When would that be? When Mars has a population of millions? Yes that's about it. It won't be this decade :-) You seem to be assuming that every inhabited lava tube must grow its own food. Well, how French of you! ;-) I'm a francophone but not French. I have been to France but only visited it for 15 minutes (the time to wait for the train change going from Germany to Belgium). But I think France has a very extrovert economy with lots of imports and exports, I don't know why you would consider it to be French to grow locally. Why can't some lava tubes become more specialized for food production, others for habitation, if the initial tube gets too crowded for farming? There will be no shortage of lava tubes for the time being. There are major industrialized nations on Earth that get by fine without 100% food self-sufficiency. I live in densely-populated Japan. My kiwi fruit comes in from sparsely-populated New Zealand. A lovely country. I really liked my trip over there. I hope you don't buy their japanese grown cantaloupe to often :-) [For those who don't know Japan, they have some special kind of cantaloupe which is horrendously expensive, something like 6000 yens or 60 US$ per fruit] To repeat: greenhouses on the Martian surface will get exactly one benefit from being on the surface: direct daytime pass-through of sunlight at frequencies useful for photosynthesis. That's IT. Everything else about being on the surface is just a source of added problems. Solving problems costs money. Money that nobody will pay if there are cheaper solutions that are just as good. Yes that is the benefit. The benefit of being underground is that you get radiation protection and I'm not sure that is needed for plants. The lost of heat, might not be a serious problem either. The habitat in the cave will be automatically very well insulated because it is in a vacuum in a cave, you will need to radiate heat away. And because their is no outside atmosphere (or very little in the case of Mars) lost of heat is only through radiation. Which benefit and and which cost are the greatest I don't know. Radiating all the heat through the greenhouse at night, at least on the Moon is problematic, so heating the greenhouse at night would probably be done. That is not very difficult. Is it cheaper to do than to collect the energy on the surface and sending it to an underground greenhouse, I don't know. Alain Fournier |
#18
|
|||
|
|||
Technologies for Moon mission useable for missions further out
"Any colony on the Moon or Mars will have to deal with various sorts
of organic waste somehow. Composting it into soil is probably the best solution." Methane digesters would be better, especially if you're energy- constrained. You could even burn the methane for low-level illumination, not just space heating and cooking. The heat input requirements for biogas reactors are a bit high, perhaps, but this is a good use of solar heat and low-level process heat; and production need not be continuous if you have a way to store methane in some quantity. So you could wait for the sun -- even if, on the Moon, that's a long wait and a lot of storage. The smaller dead-end lava tubes have potential for large-scale gas storage. You might increase the effective energy yield from the methane store by sinking its heat into the surface geology and the sky during cold periods, to chill it for higher compression, then exploiting the greater temperature differential from daytime solar heat to drive Stirling cycle generators. Chilling it is a good idea just from the point of view of reducing storage requirements, though. Achieving the needed gas mixtures for anaerobic bacteria wouldn't be difficult in environments where there's only trace O2 to begin with. But wouldn't you still want to compost stuff to fertilize your crops? I don't think so. Biogas reactors can yield good fertilizer, sooner than a compost heap. The whole process is not much different from composting, actually, more of an acceleration of composting than a diversion from it, with a very useful byproduct in the form of methane. Extraterrestrial colonization would have to develop to a fairly high scale and high comfort level before these sorts of economies of resource recycling would matter so little that people would resort to composting. I think colonists would sell their own table scraps, houseplant clippings and sewage to bioreactor operators as soon as a colony had any kind of market economy at all. Not only would they get a good price, they might *need* to get a good price -- in order to afford to buy methane for heating, cooking and lighting. Walls and ceilings of living spaces might be significantly taken up by greenery, not just for aesthetics, to relieve stark living conditions, to grow greens for salads, and to earn credits for CO2-O2 recycling, but also to generate clippings for sale to methane & fertilizer producers. It would be different on the Moon, running mostly on a two-week cycle (expansion in the "morning", consolidation around "twilight") rather than continuously and more stably, as on Mars. But many of the same technologies and lifestyle adaptations would apply to Mars. -michael turner On Jun 19, 9:49 pm, Robert Heller wrote: At Thu, 17 Jun 2010 23:15:06 EDT Alain Fournier w rote: Someone last year grew some plant in a Moon regolith imitation. It isn' t the most fertile soil but you can grow stuff in it. You then compost th e plants that grew in the regolith to have a fertile ground for farming. So at first fertile soil would be in limited supply, but with time you can make as much as you want. Organic waste = soil. This is pretty much where 'fertile' soil on the earth came from originally. Yes, it takes time. Any colony on the M oon or Mars will have to deal with various sorts of organic waste somehow. Composting it into soil is probably the best solution. -- Robert Heller -- Get the Deepwoods Software FireF ox Toolbar! Deepwoods Software -- Linux Installation and Administratio nhttp://www.deepsoft.com/ -- Web Hosting, with CGI and Database -- Contract Programming: C/C++, Tcl/Tk |
#19
|
|||
|
|||
Technologies for Moon mission useable for missions further out
"Someone last year grew some plant in a Moon regolith imitation. It isn't the most fertile soil but you can grow stuff in it." In the sense of providing support for roots and holding moisture, perhaps. However, there seem to be qualitative differences between lunar regolith simulant and real lunar regolith, none of them good: http://www.lpi.usra.edu/decadal/leag/DavidJLoftus.pdf http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2193.pdf To a reasonable first approximation, this stuff is nanometric silicon oxide, subject to meteoritic and space-radiation processes that leave the dust particles with lots more sharp edges -- at least when compared to their terrestrial semi-analogues like official NASA lunar regolith simulant. Nasty stuff you wouldn't want accumulating in your lungs or wending its way through your GI tract. This situation might argue for making your own dirt, by grinding up rocks with less hazardous material and chemical properties. Grinding up rocks to make soil? A waste of energy? Perhaps not. Maybe it would just be a by-product of the sort of machining that would fall right out of tunneling, and in general out of developing underground habitat. Lava tubes are, of course, made by volcanic lava flows. Volcanic processes produce rich soil on Earth. (The biggest carrot I ever saw was at a market in the Aso-san caldera on Kyushu in Japan.) Perhaps the Moon and Mars are much the same in this respect, they've just never had plants taking any advantage of it. -michael turner On Jun 19, 9:49 pm, Robert Heller wrote: At Thu, 17 Jun 2010 23:15:06 EDT Alain Fournier w rote: Someone last year grew some plant in a Moon regolith imitation. It isn' t the most fertile soil but you can grow stuff in it. You then compost th e plants that grew in the regolith to have a fertile ground for farming. So at first fertile soil would be in limited supply, but with time you can make as much as you want. Organic waste = soil. This is pretty much where 'fertile' soil on the earth came from originally. Yes, it takes time. Any colony on the M oon or Mars will have to deal with various sorts of organic waste somehow. Composting it into soil is probably the best solution. -- Robert Heller -- Get the Deepwoods Software FireF ox Toolbar! Deepwoods Software -- Linux Installation and Administratio nhttp://www.deepsoft.com/ -- Web Hosting, with CGI and Database -- Contract Programming: C/C++, Tcl/Tk |
#20
|
|||
|
|||
Technologies for Moon mission useable for missions further out
At Mon, 21 Jun 2010 06:48:56 EDT Michael Turner wrote:
"Any colony on the Moon or Mars will have to deal with various sorts of organic waste somehow. Composting it into soil is probably the best solution." Methane digesters would be better, especially if you're energy- constrained. You could even burn the methane for low-level illumination, not just space heating and cooking. A methane digester also produces 'soil' (or at least the wherewithall to produce soil) Once the carbon and hydrogen is extracted as methane, the remaining solid matter and nitrogen is available for fertlizer. The heat input requirements for biogas reactors are a bit high, perhaps, but this is a good use of solar heat and low-level process heat; and production need not be continuous if you have a way to store methane in some quantity. So you could wait for the sun -- even if, on the Moon, that's a long wait and a lot of storage. The smaller dead-end lava tubes have potential for large-scale gas storage. You might increase the effective energy yield from the methane store by sinking its heat into the surface geology and the sky during cold periods, to chill it for higher compression, then exploiting the greater temperature differential from daytime solar heat to drive Stirling cycle generators. Chilling it is a good idea just from the point of view of reducing storage requirements, though. Achieving the needed gas mixtures for anaerobic bacteria wouldn't be difficult in environments where there's only trace O2 to begin with. But wouldn't you still want to compost stuff to fertilize your crops? I don't think so. Biogas reactors can yield good fertilizer, sooner than a compost heap. The whole process is not much different from composting, actually, more of an acceleration of composting than a diversion from it, with a very useful byproduct in the form of methane. It might make sense to do a mixture and/or do different things with different sorts of waste products. Eg kitchen waste (vegatable trimmings, pea pods, etc.) might be composted rather then fed into the biogas system. Toilets would feed the biogas system and 'grey' water (typically washing waste water, with soap in it) will be processed another way. Extraterrestrial colonization would have to develop to a fairly high scale and high comfort level before these sorts of economies of resource recycling would matter so little that people would resort to composting. I think colonists would sell their own table scraps, houseplant clippings and sewage to bioreactor operators as soon as a colony had any kind of market economy at all. Not only would they get a good price, they might *need* to get a good price -- in order to afford to buy methane for heating, cooking and lighting. Walls and ceilings of living spaces might be significantly taken up by greenery, not just for aesthetics, to relieve stark living conditions, to grow greens for salads, and to earn credits for CO2-O2 recycling, but also to generate clippings for sale to methane & fertilizer producers. It would be different on the Moon, running mostly on a two-week cycle (expansion in the "morning", consolidation around "twilight") rather than continuously and more stably, as on Mars. But many of the same technologies and lifestyle adaptations would apply to Mars. Yes indeed! -michael turner On Jun 19, 9:49 pm, Robert Heller wrote: At Thu, 17 Jun 2010 23:15:06 EDT Alain Fournier w rote: Someone last year grew some plant in a Moon regolith imitation. It isn' t the most fertile soil but you can grow stuff in it. You then compost th e plants that grew in the regolith to have a fertile ground for farming. So at first fertile soil would be in limited supply, but with time you can make as much as you want. Organic waste = soil. This is pretty much where 'fertile' soil on the earth came from originally. Yes, it takes time. Any colony on the M oon or Mars will have to deal with various sorts of organic waste somehow. Composting it into soil is probably the best solution. -- Robert Heller -- Get the Deepwoods Software FireF ox Toolbar! Deepwoods Software -- Linux Installation and Administratio nhttp://www.deepsoft.com/ -- Web Hosting, with CGI and Database -- Contract Programming: C/C++, Tcl/Tk -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software -- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database -- Contract Programming: C/C++, Tcl/Tk |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
NASA seeks ideas for mission, capailities and technologies | Jacques van Oene | News | 0 | November 11th 04 03:59 PM |
multiple launch moon mission vs. Single Launch moon missions | Fred K. | Policy | 2 | March 20th 04 02:29 PM |
New moon and mars missions... | Robert Kent | Space Shuttle | 6 | January 18th 04 08:06 PM |
All Moon Missions Were Unmanned | OM | History | 5 | August 12th 03 09:07 PM |
All Moon Missions Were Unmanned | Bill Sheppard | Misc | 1 | July 23rd 03 04:51 PM |