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Water out of stone (or C1 Chondrites) by KelvinZero on 14 Apr, 2013 03:29
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Hi, Im just trying to understand the availability of volatiles in near earth objects.
Here is an example of a sort of rock that hits earth on occasion:
http://en.wikipedia.org/wiki/CI_chondrite#Chemical_composition
Note that it claims this type of meteorite is 17%-22% water by weight, but it is "tied up in water-bearing silicates". Im hazy on my chemistry but I think this is saying something along the lines of, sure it has lots of water, but so does concrete.
So what would be involved in extracting this water? -
#1 by gbaikie on 14 Apr, 2013 06:13
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Hi, Im just trying to understand the availability of volatiles in near earth objects.
Here is an example of a sort of rock that hits earth on occasion:
http://en.wikipedia.org/wiki/CI_chondrite#Chemical_composition
Note that it claims this type of meteorite is 17%-22% water by weight, but it is "tied up in water-bearing silicates". Im hazy on my chemistry but I think this is saying something along the lines of, sure it has lots of water, but so does concrete.
So what would be involved in extracting this water?
Roughly heating it to about 1000 C [1800 F]
Hydrated Portland cement has about this much water in it.
"In addition the water that is chemically bound with the cement in the hydration process must be accounted for. The water bound with the cement is in the range of 0.22 to 0.24 of the cement content. "
http://www.cement.org/tech/faq_moisture_content.asp
Concrete is mixture of Portland cement, sand, and gravel.
So if just used the Portland cement and mixed water with it, and let it harden and dry out, that could be similar chondrite space rock.
Making the Portland cement:
"Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a calcining temperature, which is about 1450 °C for modern cements. "
http://en.wikipedia.org/wiki/Portland_cement
So I would say up to 500 C should remove some water, 1000 C might remove most, and 1500 C should remove all.
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#2 by Robotbeat on 14 Apr, 2013 06:24
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I would bet low pressure helps remove water as well.
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#3 by Solman on 16 Apr, 2013 03:00
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I wonder if electric heating of a small region of the asteroid might work. What I have in mind is bagging the asteroid and drawing it in to contact with a...plasma torch? resistance heater? arc heater? to liberate water vapor that would be contained by the bag for use as propellant by a resistojet. The heating element could be on a pole that could be extended at various angles as parts of the asteroid are consumed.
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#4 by Warren Platts on 16 Apr, 2013 06:08
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I stuck a chunk of concrete in a microwave oven, once, just to see what would happen. It definitely started steaming. Didn't have an accurate scale to measure the before-and-after weight, however.
Here's a link that addresses the topic; it's about hydrated minerals in Martian regolith, but the principle is the same.
http://old.marssociety.org.au/library/coober_pedy_ISRU_AMEC.pdf
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#5 by kkattula on 16 Apr, 2013 09:49
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Get a very big aluminized Mylar bag with a transparent window.
Put asteroid inside and seal.
Erect large inflatable solar concentrator and focus on bag window.
Wait for volatiles to boil off and extract through a valve in the bag.
Continue heating asteroid until it melts.
Insert heat resistant pipe through another valve to the centre of the molten asteroid.
Flow high pressure nitrogen through pipe.
Blow a nice big bubble, leaving a thick shell.
Seal pipe, and allow to cool.
Cut holes for airlock, etc.
Outfit as habitat with excellent radiation protection.
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#6 by tnphysics on 17 Apr, 2013 16:05
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Sounds like the battlestations from John Ringo's Troy Rising series, though those had massive engines, true artificial gravity (not by rotation), enormous weapons systems, and also contained the final targeting mirrors for the concentrated solar system, which was apparently focused (this is impossible in real life without a sun pumped laser) to the point of being essentially a devastating broadband laser weapon.
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#7 by Lar on 17 Apr, 2013 16:42
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Get a very big aluminized Mylar bag with a transparent window.
Put asteroid inside and seal.
Erect large inflatable solar concentrator and focus on bag window.
Wait for volatiles to boil off and extract through a valve in the bag.
Continue heating asteroid until it melts.
Insert heat resistant pipe through another valve to the centre of the molten asteroid.
Flow high pressure nitrogen through pipe.
Blow a nice big bubble, leaving a thick shell.
Seal pipe, and allow to cool.
Cut holes for airlock, etc.
Outfit as habitat with excellent radiation protection.
Hmm... what is the melting point of mylar? Or of the transparent window? As soon as any volatiles escape there is going to be some heat transfer to the bag via conduction I would think... (well there would be radiative heat transfer all along)
So while the first part might work, (although I'm doubtful)... I am extremely dubious that the second part would work... as soon as any of the asteroid melts, the residual rotation might, or outgassing from pockets, might, fling molten bits at the bag.
What am I missing conceptually? -
#8 by KelvinZero on 24 Apr, 2013 22:35
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Making the Portland cement:
Thanks for that,
"Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a calcining temperature, which is about 1450 °C for modern cements. "
http://en.wikipedia.org/wiki/Portland_cement
So I would say up to 500 C should remove some water, 1000 C might remove most, and 1500 C should remove all.
So apparently the basic process is well understood and something we actually do regularly on an industrial scale.
http://en.wikipedia.org/wiki/Clinker_(cement)
http://en.wikipedia.org/wiki/Calcination
So this just leaves issues of how to do it in zero-g. Repeatedly sealing floating grit into air-tight containers seems a recipe for problems.
How about if the bag wrapping the asteroid was itself made airtight? This would only need to be sealed once, eg with a glue so it works even if grit gets in the way.
Then you could have some sort regolith grabber moving inside this bag. Incorporated into the grabber is an electric heater, perhaps powered by the 40kw solar panels I think were mentioned for the SEP.
It collects a fist-full of asteroid material, heats it into a clinker brick and volatiles are released inside the bag. A pipe from the bag with a filter to block grit extracts the volatiles over time, and from that point it is a more conventional problem.
By the end of the process you have a bag full of clinker bricks and tanks full of volatiles.
Another question is the design of the regolith grabber. My first thought was literally a robotic hand, but perhaps that wouldnt work so well with floating regolith. How about you maintain some pressure of volatiles inside the bag in order that you can use suction to gather regolith. This could make the grabber a function of the pipe for extracting volatiles.
(edit: just noticed some of this was similar to Solman's post. no plagiarism intended
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#9 by timothyz on 25 Apr, 2013 05:39
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Too much information. I must say that this information is new to me as i ma not so physics or sort of a space geek actually but i like to know about space the myths and facts. Thank you for sharing such information.
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#10 by JohnFornaro on 25 Apr, 2013 12:43
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Get a very big aluminized Mylar bag with a transparent window.
Put asteroid inside and seal.
Erect large inflatable solar concentrator and focus on bag window.
Wait for volatiles to boil off and extract through a valve in the bag.
Continue heating asteroid until it melts.
Insert heat resistant pipe through another valve to the centre of the molten asteroid.
Flow high pressure nitrogen through pipe.
Blow a nice big bubble, leaving a thick shell.
Seal pipe, and allow to cool.
Cut holes for airlock, etc.
Outfit as habitat with excellent radiation protection.
If you've been following my line of reasoning lately, you'll agree that most of this technology is already at *cough* TRL6 *cough*. -
#11 by Lar on 25 Apr, 2013 13:49
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Get a very big aluminized Mylar bag with a transparent window.
Put asteroid inside and seal.
Erect large inflatable solar concentrator and focus on bag window.
Wait for volatiles to boil off and extract through a valve in the bag.
Continue heating asteroid until it melts.
Insert heat resistant pipe through another valve to the centre of the molten asteroid.
Flow high pressure nitrogen through pipe.
Blow a nice big bubble, leaving a thick shell.
Seal pipe, and allow to cool.
Cut holes for airlock, etc.
Outfit as habitat with excellent radiation protection.
If you've been following my line of reasoning lately, you'll agree that most of this technology is already at *cough* TRL6 *cough*.
I see what you did there. -
#12 by alexterrell on 27 Apr, 2013 16:26
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If the space craft has 40KW of electric power handy, how much does a 40KW laser weigh? That could extract enough volatiles and get the asteroid nicely chopped up into parcel sized loads for collection by
FedexNASA.
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#13 by KelvinZero on 27 Apr, 2013 22:44
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haha.. I wonder if someone would complain about that..
Germany 40kW laser gun
But that brings up a good point. These smaller asteroids may be actual boulders? They wouldnt have much gravity to hold themselves together. -
#14 by Lar on 28 Apr, 2013 04:49
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haha.. I wonder if someone would complain about that..
Nice story. If only that German defense contractor sold sharks.
Germany 40kW laser gun
But that brings up a good point. These smaller asteroids may be actual boulders? They wouldnt have much gravity to hold themselves together.
Agree that many smaller asteroids may be agglomerations of loose material. That presumably makes capture easier, though -
#15 by KelvinZero on 28 Apr, 2013 07:47
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All the asteroids I have seen so far have been rubble piles. I was wondering if the smaller ones might turn out to be solid rocks, maybe even spinning too fast for gravity to hold loose bits together. In this case my regolith sucking idea is no good. In any case the whole thing will not be dust so we need some approach for larger pieces.
Would a laser be a good tool for cutting up lumps of rock, or is that just science fiction? I googled "Mining laser" and all I found were video games.
The idea of no teeth to wear away is attractive. If it works at all we probably dont need a 40 kW laser just for the cutting. So what if it takes a month if there are years between missions.
(edit)
found this:
earth boring with laser energy
Concept of drilling for oil with lasers. Mentions 2.5kW for experiments.
Cutting stone with water and light
More about engraving with 100w lasers, but says deep cuts are possible (but not that practical) -
#16 by smoliarm on 28 Apr, 2013 09:17
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So what would be involved in extracting this water?
The short answer is "none", sorry
The first trick is that there is no actual H20 in CI's (note that correct name is CI, not C1). The percentage shown in wiki is a *hypothetical* amount of H2O required to convert primordial carbides (e.g., cohenite), phosphides (schribersite) and sulphides (troilite) into carbonates, phosphates, and sulphates, respectively.
However, there is no chemical way to convert, say, FeSO4 back to FeS (troilite) + H2O -- without adding some H2.
So, the statement from wiki
>>The water is not occurring freely, but is rather tied up in water-bearing silicates.
should be read as "water was largely involved in formation of some minerals, but most of its hydrogen is GONE"
Therefore, heating CI chondrite to 2000 K would produce some water but only about 0.05% rather then 15% of bulk meteorite weight.
One more problem - CI chondrites is an extremely rare type of meteorites. E.g., typical price for ordinary chondrite is around 1 $ per gram. For Tagish Lake (CI 2) specimens it's more like $1000 per gram.
Most likely, CIs originate from some comet, not from asteroid. Therefore, one should not expect that captured asteroid will have water content on the order of 10%, not even 1%. -
#17 by KelvinZero on 28 Apr, 2013 10:25
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Hi smoliarm,
Im not very educated in this subject so I might be using the wrong terms. I think C1 Chondrite is in fact the term for the meteorite fragments that we find that I guess have gone through extreme heating on arrival.
My (weak) understanding is they are hard to find because the asteroids they come from tend to explode when they hit our atmosphere, due to the volatiles they contain.
What I am really interested in is the amount of water available in asteroid material before it becomes a meteorite.
Here is a quote from that Keck paper that initially suggested capturing an asteroid:
A 500-t, carbonaceous C-type asteroid may contain up to 200 t of volatiles (~100 t water and ~100 t carbon-rich compounds), 90 t of metals (approximately 83 t of iron, 6 t of nickel, and 1 t of cobalt), and 200 t of silicate residue)
Another quote:
we are selecting a carbonaceous asteroid. Asteroids of this type and size are known to be too weak to survive entry through the Earth’s atmosphere, so then even if it did approach the Earth it would break up and volatilize in the atmosphere.
A third quote:
Carbonaceous asteroids are the most compositionally diverse asteroids and contain a rich mixture of volatiles, complex organic molecules, dry rock, and metals. They make up about 20% of the known population, but since their albedo is low, they may be heavily biased against detection in optical surveys. ----. Carbonaceous asteroid material similar to the CI chondrites is easy to cut or crush because of its low mechanical strength, and can yield as much as 40% by mass of extractable volatiles, roughly equal parts water and carbon-bearing compounds. The residue after volatile extraction is about 30% native metal alloy similar to iron meteorites [12].
I admit it is probably risky to base my understanding on a single paper whose focus is not so much on space science as why we should give them 2.5 billion dollars
Here is the paper, posted by yg1968 in another thread.
http://www.kiss.caltech.edu/study/asteroid/asteroid_final_report.pdf -
#18 by smoliarm on 28 Apr, 2013 12:23
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Hi smoliarm,
Fortunately for us, this is not true. Only the fusion crust of meteorite experience some heating (some hundreds °C, depending on entry mode), and this is VERY thin (~0.5 mm) outer layer. The rest of meteorite does not see any heating above 50°C at all. It's hard to believe, I guess, but this is a fact.
...
I think C1 Chondrite is in fact the term for the meteorite fragments that we find that I guess have gone through extreme heating on arrival.
I processed and analyzed a number of meteorites, both stones and irons. They all contain a lot of troilite - mineral which decomposes very rapidly even at 200 °C. And this is not the only evidence that meteorites do not go through bulk heating during atmospheric entry.
I understand, that this is something contra-intuitive, given the violent-looking meteorite entry, but this is a well-established fact: meteorite fragments reaching the ground did not see any serious heating, just a brief mechanical shock.Quote...
My (weak) understanding is they are hard to find because the asteroids they come from tend to explode when they hit our atmosphere, due to the volatiles they contain.
No, it is because they are very rare. And, once again, there are strong evidences suggesting that CI chondrites do not originate from asteroids. Therefore, it's not a good idea to use their composition to estimate result of asteroid capture mission.
BTW, the explosions here are NOT due to "volatiles" in common sense. It is a release of huge kinetic energy, which results in rapid heating of *unlucky* part of meteor up to 3000-3500 K. At such T, for example, metallic iron IS volatile just as water ice at 400°C, and of course it explodes shuttering the meteor body apart. But the rest of material (the *lucky* parts) do not see heating at all.QuoteWhat I am really interested in is the amount of water available in asteroid material before it becomes a meteorite.
Trust me, the amount of water in parental asteroid and in meteorite originating from this asteroid is essentially the same.QuoteHere is a quote from that Keck paper that initially suggested capturing an asteroid:
A 500-t, carbonaceous C-type asteroid may contain up to 200 t of volatiles (~100 t water and ~100 t carbon-rich compounds), 90 t of metals (approximately 83 t of iron, 6 t of nickel, and 1 t of cobalt), and 200 t of silicate residue)
It is just an unfortunate coincidence of letter "C" in C-type asteroids and in C-chondrites, they have nothing to do with each other. Especially, this is true about composition.
It is a common misconception that C-type asteroids are made of C-chondrite material - this is NOT true.
In fact, we do not know for sure that C-type asteroids are carbonaceous at all. The spectral data alone do not allow to make such conclusion, and we do not have any other data so far.
I do not know, how the authors got the above estimate of asteroid composition, but I can assure you it does not follow from meteorite data. All I can tell you -- they would have pretty hard time with reviewers and editors if they try to publish this in journals like EPSL or GCA.
One more detail - most of "carbon-rich compounds" in carbonaceous chondrites are carbides, and they are REFRACTORY, not volatile.QuoteI admit it is probably risky to base my understanding on a single paper whose focus is not so much on space science as why we should give them 2.5 billion dollars
Well, in my opinion asteroid capture is a great idea which has huge scientific value. So, there is no risk from scientific side. With asteroid mining it is quite different story. But, even if they fail the commercial part of the enterprise, we scientists still get our samples, no risk So, what the hell, give them these $B and let them fail water extraction 
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#19 by JohnFornaro on 28 Apr, 2013 14:23
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And, once again, there are strong evidences suggesting that CI chondrites do not originate from asteroids. Therefore, it's not a good idea to use their composition to estimate result of asteroid capture mission.
Quote from: KeckCarbonaceous asteroids are the most compositionally diverse asteroids and contain a rich mixture of volatiles, complex organic molecules, dry rock, and metals. They make up about 20% of the known population, but since their albedo is low, they may be heavily biased against detection in optical surveys... yada yada
Smoliarm: Do you agree with the Keck assessment?Quote from: SmoliarmI do not know, how the authors got the above estimate of asteroid composition, but I can assure you it does not follow from meteorite data. All I can tell you -- they would have pretty hard time with reviewers and editors if they try to publish this in journals like EPSL or GCA.
As always, I'm not getting something. BTW, there's a poster around here who should read your comments. I wouldn't dream of "forcing" them to do so.
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