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Post by davidm on Jun 15, 2012 6:01:32 GMT 9.5
One of the arguments I've heard for the belief in unlimited growth is that once we have exhausted our resources on earth we have a whole solar system available for exploitation. Applying the principle of EROI to outer space how do you ever come out on the positive side of the ledger? This fellow doesn't think you can. Plug in cost in place of energy if you like. |
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Post by LancedDendrite on Jun 15, 2012 10:43:51 GMT 9.5
The ultimate aim of asteroid mining and off-world resource exploitation is not to provide energy or materials to Earth. It is to sustain an interplanetary civilisation with the natural resources that it will inevitably require. However, Planetary Resources' plan includes mining platinum group metals on near-earth asteroids if they find it economical. Platinum-group elements are just about the only thing that might be feasible to return to Earth, as they are fairly rare planet-side, have a decent density and can be found in fairly good quantities on certain asteroids. In particular, if they can find palladium and iridium in large quantities then it may be quite economic. When it comes to space-based sources of energy for planet-side use however, I would agree that current proposals are uneconomical. I recall that Kirk Sorenson said once during one of his videos that when he worked for NASA he had a look at the effect of launch costs on solar power satellites and found that they were uneconomical even with a launch cost of $0/pound. Helium-3 mining for use in fusion reactors is another concept that gets bandied around often. I personally see little use for it outside of nuclear fusion rocket engines assembled within the gravity well of the He-3 mining site. |
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Post by anonposter on Jun 15, 2012 19:13:00 GMT 9.5
One of the arguments I've heard for the belief in unlimited growth is that once we have exhausted our resources on earth we have a whole solar system available for exploitation. Indeed we do, in fact we could build thousands of times the Earth's surface area in the form of space settlements. Applying the principle of EROI to outer space how do you ever come out on the positive side of the ledger? This fellow doesn't think you can. Plug in cost in place of energy if you like. Well he doesn't really back up his arguments very well (or even at all, if he did an EROI calculation I couldn't see it). I should note that energy requirements to get into space aren't actually as high as many people seem to think they are (if we only had to pay the energy costs at the rate we pay for electricity then getting to space would be really cheap, once we get space elevators that's probably what it'll end up costing). But anyway, the plan mostly isn't so much to return whatever we find to the Earth (though precious metals may well turn out to be worth returning) but to not have to blast up all the materials needed for our space settlements from Earth (the moon has a lower gravity well and no atmosphere allowing for rocketless launch of raw materials (with a mass driver) while asteroids have even less gravity and in many cases better compositions). I'll also just note that the claim about no hydrocarbons in asteroids is false (I've seen estimates that the asteroids may have a lot of hydrocarbons, though very unlikely to be worth sending them down to Earth, they'd be used as rocket fuel or feedstock for plastics). When it comes to space-based sources of energy for planet-side use however, I would agree that current proposals are uneconomical. I recall that Kirk Sorenson said once during one of his videos that when he worked for NASA he had a look at the effect of launch costs on solar power satellites and found that they were uneconomical even with a launch cost of $0/pound. Those who've looked at it from a space resources point of view have tended to find that if you got the resources from the moon or asteroids that the economics actually look quite good (projections that they could be cheap enough to compete with nuclear). Of course how that'd turn out in practice is another matter (I'd say that of the renewables it's the one with the best hope of actually being able to do what we need). Helium-3 mining for use in fusion reactors is another concept that gets bandied around often. I personally see little use for it outside of nuclear fusion rocket engines assembled within the gravity well of the He-3 mining site. Rocketry is really the only application I can see where not having undirectable neutrons (which are most of the energy in D+T and nearly half in D+D) is actually worth the extra difficultly of using 3He. Though I suspect by the time we're using fusion rockets in a big way that we'll be getting the 3He from the gas giants Saturn, Uranus and Neptune (Jupiter's gravity well is a big steep, not to mention it's ultra-strong radiation belts) and not the moon. |
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Post by davidm on Jun 15, 2012 20:24:33 GMT 9.5
In your space colony I don't get how you can increase biomass from nonearth sources.
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Post by Nick P. on Jun 15, 2012 20:35:18 GMT 9.5
In your space colony I don't get how you can increase biomass from nonearth sources. Why not? Among the different kinds of asteroids out there you can find water, carbon, nitrogen and everything else that life requires. Provide light, atmosphere and nutrients and things can be made to grow. |
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Post by anonposter on Jun 15, 2012 21:14:31 GMT 9.5
The first space settlements will probably be importing from Earth (though we should be able to get CELES refined enough to make most of the food there for the very first one, a successor to Biosphere 2 which takes account of the lessons learnt there would be very useful for that) but over time as we learn they'll become more and more self-sufficient.
As Nick P. mentioned, there's plenty of CHON out there (if we start out with lunar mining we'll probably end up getting a lot of nitrogen, hydrogen and carbon from Earth but even then most of the mass won't be CHON (note that the reference design in the NASA Ames-Stanford '75 summer study was almost 10 million tonnes, 9.9 million of which were radiation shielding)).
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Post by davidm on Jun 16, 2012 3:47:52 GMT 9.5
So how far have we gotten in creating expandable biospheres on earth which can independently support human life with nothing added from the outside but sunlight and nonorganic materials that one might find on an asteroid? It would seem that one would need to model success here before one would try it in the much more challenging conditions of outer space.
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Post by Nick P. on Jun 16, 2012 5:05:12 GMT 9.5
So how far have we gotten in creating expandable biospheres on earth which can independently support human life with nothing added from the outside but sunlight and nonorganic materials that one might find on an asteroid? It would seem that one would need to model success here before one would try it in the much more challenging conditions of outer space. Biosphere II wasn't exactly a smashing success admittedly but you learn from your mistakes and try again, which considering we haven't built Biosphere III yet I wouldn't write the concept off just yet. Two points though; first is that space colonies will in all likelihood be much larger and larger biospheres are probably more stable than small ones, second is that there is no reason to limit ourselves to exclusively biological cycles. If the nitrogen fixing plants aren't fixing enough nitrogen, then do it synthetically to make up the difference. If there's not enough C02 to let the plants keep growing then add some more, if the cycle swings the other way with too much C02 being released then separate it out and store it in tanks until the cycle swings back again. Saying that it must be a completely 'natural' biosphere with nothing other than sunlight being let in is needlessly limiting when a degree of active management will probably make the whole affair immensely easier. Finally what's all this about inorganic asteroid materials? If we're working with CHON then those by definition are 'organic' chemicals. Carbon, nitrogen, oxygen, hydrogen, phosphorus, sulfur, that's what life is made of. Knowing a thing or two about hydroponics plants will grow quite happily with their roots in water containing nitrates and the trace elements. EDIT: Thinking further on the topic, yes space is a challenging environment but it's challenging in very consistent ways. Plus it has upsides as well, the constant strong sunlight makes things possible that aren't practical on Earth, plants can be given exactly as much or as little sunlight for as long or short as they need for absolutely optimal growth. There are no seasons in space, there are no days and nights in space, there are no late frost, droughts, hurricanes or driven snow in space. If these things are needed or desirable they can be replicated by the configuration of the habitat and optimized to our needs. |
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Post by anonposter on Jun 16, 2012 5:47:28 GMT 9.5
Biosphere 2 came pretty close, I'd say the biggest problem was the unexpected drop in oxygen levels (which required oxygen to be injected from outside) and CO2 levels also seemed to be getting a bit high and were fluctuating quite wildly (they had to use the scrubber at times).
They lost quite a few species as well (but had carefully selected them so as to be able to handle the loss of some of them).
The second crew of Biosphere 2 managed to avoid using stored food (which the first crew did need), at least until they were sabotaged (there were a lot of cranks involved in it making life difficult for the real scientists).
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Post by anonposter on Jun 16, 2012 5:51:41 GMT 9.5
I should just add a note that larger space settlements are likely to be big enough to have their own weather including clouds and natural rainfall.
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Post by davidm on Jun 16, 2012 8:36:04 GMT 9.5
So how far have we gotten in creating expandable biospheres on earth which can independently support human life with nothing added from the outside but sunlight and nonorganic materials that one might find on an asteroid? It would seem that one would need to model success here before one would try it in the much more challenging conditions of outer space. Well then presumably a much larger biosphere would be built on earth first. And that model would have to be successful before we took it to outer space. I didn't say that. I included adding the kind of materials one would find on an asteroid. So is calcium an organic material too? My understanding is that elements can be in organic or inorganic form. If there is no distinction then the difference between organic and nonorganic is removed. Still its hard to imagine that if you couldn't model a successful biosphere here you could in outer space. The advantages on earth are so manifest. |
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Post by anonposter on Jun 16, 2012 21:17:33 GMT 9.5
Well then presumably a much larger biosphere would be built on earth first. And that model would have to be successful before we took it to outer space. It would help, though having some like Biosphere 2 mostly successful on Earth (or at least more successful than it was) would probably give enough confidence to be willing to try it in space (though with a lot of backups in case it doesn't work, I imagine the first space settlement will have a lot of stored food, backup CO 2 scrubbers, etc). Besides, we'll probably be doing it gradually with space hotels and moon and asteroid bases before we actually try to build a space settlement which will likely end up using some of the techniques of the full scale space settlements as a supplement to the more proven but wasteful technologies we're currently using. So is calcium an organic material too? My understanding is that elements can be in organic or inorganic form. If there is no distinction then the difference between organic and nonorganic is removed. The distinction is more in the compounds not the elements (and can itself be a source of confusion, the difference first appeared back when people didn't know that vitalism was wrong). For the most part organic chemistry is carbon based compounds. But anyway, there's quite a bit of Ca in asteroids (at least if you mine the right ones) so I wouldn't worry about running out of it. Still its hard to imagine that if you couldn't model a successful biosphere here you could in outer space. The advantages on earth are so manifest. You could use artificial lighting if you wanted things to grow 24/7 (some small scale experiments have done exactly that) but the whole point of space settlement is to get people living off earth. Besides, I'm pretty sure you could model a successful biosphere on Earth, Biosphere 2 whilst they had their problems came pretty close. |
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Post by joffan on Jun 18, 2012 12:53:34 GMT 9.5
The other thing that should be reasonably obvious is the elemental mix that made the Earth is not so very different from the elemental mix that is out there in the solar system. So there shouldn't be desperate shortage of the elements themselves, even if they are not always found in convenient compounds for supporting life. A suitable energy source can take care of that.
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Post by eclipse on Aug 11, 2012 22:53:22 GMT 9.5
One shot into space People often argue that space mining is ridiculous and impossible given the sheer cost in energy to launch ships into space. It's so expensive that way that even if a ship were being launched to mine a pure platinum asteroid, the costs to blast the ship up there and back are so prohibitive there's no economic point in doing it. But what if the trip were only one way and then grew in exponential returns? What if, one day, instead of climbing up out of the gravity well and back for every single shipment of ore, we just fire one ship up the gravity well and it STAYS OUT THERE! Imagine a future ship with whizz-bang new future AI's and robotics. It's not necessarily even manned. It's not just a ship, but an automated factory. It's designed to fly out there and replicate itself. This ship is injected into orbit with the asteroids where it replicates by mining ores and energy (uranium dust or the electromagentic energy between Jupiter and it's moons or whatever!) and water for hydrogen and anything else this ship needs. Viewed through tomorrow's exponential growth in AI's and robotics, our ship becomes a self-replicating viral robot, spreading through the asteroid belt until it reaches a critical mass. Fleets of ships would collect and manufacture what ever we required, while other ships gathered water for splitting into hydrogen to shoot their payloads back to Earth. Then, eventually, they would return their cargo, with carbon-fibre parachutes built in. Shooting one self-replicating super-AI manufacturing ship out there would return an exponential yield of goods that would eventually return free of the gravity well so many 'space mining critics' are worried about. We'd literally have gifts raining down from the skies, aerobraking and parachuting down to safe locations. Maybe some of it will be parked in orbit as space-based solar power. Maybe one particularly huge gift will be a space-elevator. Who knows? Now, if you must, you can add in DOZENS of ships, and some of them with many dozens of human beings on board. We're heading into Arthur C Clarke and Isaac Asimov territory, but why not? How many of their ideas about geosync satellites have already turned into reality? Indeed, Science Fiction writer Karel Čapek invented the term Robot and now Robotics is a huge industry sponsored by enormous military, oil, medical, scientific, space exploration and even gaming industries! "The word robot was introduced to the public by the Czech interwar writer Karel Čapek in his play R.U.R. (Rossum's Universal Robots), published in 1920.[39] The play begins in a factory that makes artificial people called robots, though they are closer to the modern ideas of androids, creatures who can be mistaken for humans. They can plainly think for themselves, though they seem happy to serve. At issue is whether the robots are being exploited and the consequences of their treatment." en.wikipedia.org/wiki/Robot#EtymologyThe point is that with higher technology AI + robotics, it only takes one rocket. If we're patient. If we're not, then who knows how fast this leap might occur? Then instead of us trying to climb out of the gravity well all by ourselves we will one day find a hand (or many hands) reaching down to help. |
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Post by eclipse on Aug 11, 2012 23:05:47 GMT 9.5
In your space colony I don't get how you can increase biomass from nonearth sources. Why not? Among the different kinds of asteroids out there you can find water, carbon, nitrogen and everything else that life requires. Provide light, atmosphere and nutrients and things can be made to grow. burger anyone? (See Frederick Phol's Gateway trilogy). Carbon Hydrogen Oxygen Nitrogen. |
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Post by trag on Aug 16, 2012 2:54:59 GMT 9.5
In your space colony I don't get how you can increase biomass from nonearth sources. Read "Farmer in the Sky" by Robert Heinlein for a fairly detailed explanation of how the colonists turn dead Ganymedean rock into usable soil. Ah, reading further I see you've been mislead by folks who use the word "organic" in confusing ways. Organic compounds are just molecules that contain carbon atoms. The organic farming crowd uses the word completely differently, which from the context, I would guess is where you're getting your background and confusion. Plants don't need "organic" compounds in their soil in order to grow. And there's no difference between "organic" carbonate, and chemical carbonate, or nitrate, or phosphate. The molecules don't acquire special virtue in some process that makes them "organic". Organic material in soil can be helpful because the process of bacterial decomposition of organic material releases plant nutrients into the soil in a sort of natural time release manner. But you can grow plants just fine with only NO3, P, and K plus various trace elements in an aqueous solution and CO2 in the atmosphere for a carbon source. I grow aquatic plants in my aquariums, and the situation isn't far removed from the above. It can be tricky keeping the trace elements balanced. Darned Java Fern appears to sequester iron to the detriment of the other plants. So, as long as one can find plenty of N, P, K, O, C, and H in asteroids, plus a smattering of the rest of the periodic table, and if one has an energy source, then life can be made to thrive. |
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Post by trag on Aug 16, 2012 3:25:39 GMT 9.5
People often argue that space mining is ridiculous and impossible given the sheer cost in energy to launch ships into space. It's so expensive that way that even if a ship were being launched to mine a pure platinum asteroid, the costs to blast the ship up there and back are so prohibitive there's no economic point in doing it. At today's launch costs this is completely true. The cost of launching a pound into orbit using the space shuttle was approximately $10,000/lb. There's some variation in that number depending on how you do the accounting and attribute the fixed costs (ground control and support facilities) but the range I've seen is about $5000 - $20,000/lb. Until the price of gold jumped, starting about five years ago, I liked to say that one could fill the space shuttle's cargo bay to capacity with lead, launch it into orbit, magically transform the lead into gold, bring it back to Earth, and you would still lose money on the deal. Actually at the price, five years ago (~$650) you would almost break even, if not for the cost of the lead. This is the concept of von Neuman machines. We're not there yet. There is an excellent prologue in James P. Hogan's "Code of the Lifemaker" (1983) which describes how a space based von Neuman system mutates into a complex ecosystem. It seems very original, but Poul Anderson had the same idea (different setting) in his 1962 story "Epilogue". Anyway, the larger point is that at current launch costs space based industry is not economical. One could get the bulk of the material needed from space based resources and avoid the launch costs, but what kind of initial investment in terms of mass lifted from Earth would be needed? What is the minimum input mass to create an industrial infrastructure in space? Von Neuman machines are an interesting path/method, but there's little point in discussing them because we cannot build them. I guess if one is not focused on the immediate future, one could argue that limitations in Earth's (non-energy) resources are unlikely to matter, because by the time they do, we'll be capable of sending von Neuman machines into space. |
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