NASASpaceFlight.com Forum
General Discussion => Advanced Concepts => Topic started by: KelvinZero on 04/14/2013 03:29 am
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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?
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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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I would bet low pressure helps remove water as well.
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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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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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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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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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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?
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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.
Thanks for that,
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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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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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*.
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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.
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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
Fedex NASA.
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haha.. I wonder if someone would complain about that..
Germany 40kW laser gun (http://optics.org/news/3/9/21)
But that brings up a good point. These smaller asteroids may be actual boulders? They wouldnt have much gravity to hold themselves together.
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haha.. I wonder if someone would complain about that..
Germany 40kW laser gun (http://optics.org/news/3/9/21)
But that brings up a good point. These smaller asteroids may be actual boulders? They wouldnt have much gravity to hold themselves together.
Nice story. If only that German defense contractor sold sharks. :)
Agree that many smaller asteroids may be agglomerations of loose material. That presumably makes capture easier, though
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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 (http://www.industrial-lasers.com/articles/print/volume-19/issue-12/features/earth-boring-with-laser-energy.html)
Concept of drilling for oil with lasers. Mentions 2.5kW for experiments.
Cutting stone with water and light (http://www.signindustry.com/computers/articles/1999-CuttingStoneWithWater.php3)
More about engraving with 100w lasers, but says deep cuts are possible (but not that practical)
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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%.
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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
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Hi smoliarm,
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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.
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 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.
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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.
What 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.
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)
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.
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 :)
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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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.
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... yada yada
Smoliarm: Do you agree with the Keck assessment?
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.
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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There was a long thread about a year ago that discussed a lot of these same issues.
http://forum.nasaspaceflight.com/index.php?topic=28768.msg894847#msg894847
I figured a business case could maybe close if they can get the cost of their retrievers down to order $100M each, and they find enough of the 20% H20 asteroids. You'd want to crush meteoroid to a small size in a pressurized container, so you could use air flow to move things around (since there's no gravity). A processing plant massing ~130 mT based around a BA2100 module might work.
@ smoliarm: Of course you'd have to add hydrogen to FeSO4 in order to make H20; but I thought the so-called "water" was supposed to be found in hydrated, serpentine-like minerals with formulas more like (Mg,Fe)3Si2O5(OH)4. In the latter case, there is some hydrogen (4 atoms per molecule, thus you could liberate 2 H2O's per molecule).
I admit something's not adding up. E.g., just taking Mg3Si2O5(OH)4 (no heavy iron) I get a molecular weight of ~277, thus 2 water molecules only adds up to 13%. If Fe is substituted, the percentage is only 10%.
The following reference says that CI chondrites are 90% by volume made up of phyllosilicates, but if that's the case, they must be very special silicates: e.g., vermiculite, (Mg,Fe,Al)3(Al,Si)4O10(OH)2·4H2O, I can see how you can get 20% H2O, but not out of serpentines....
http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3031.pdf (see page 237)
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Smoliarm: Do you agree with the Keck assessment?
With respect to their estimate of C-asteroid composition -- NO.
BUT - this does NOT mean a thing about their paper as whole. I believe their proposal has GREAT value, and the fact that they are way too optimistic about water content - it subtracts nothing from this value.
Say, in 10 years NASA manages to capture such rock and put it into high-lunar orbit. And then it turns out that it does not have even 1% water in usable form - so what?? The rock is still there for us to study, that's the main point.
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.
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.
OK, may be it's because of these abbreviations:
EPSL = Earth and Planetary Science Letters;
GCA = Geochimica et Cosmochimica Acta;
None of these journals would allow these statement on their pages:
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)...
...Carbonaceous asteroid material similar to the CI chondrites is easy to ...
never.
This is what I mean.
But once again, this is a great proposal, which main focus is far away from composition of asteroids.
And, after all, we know almost nothing about composition of asteroids.
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I admit something's not adding up...
Yes, but it is not only about percentages :)
First:
CI-chondrites represent a unique type of meteorites, which is extremely rare.
They comprise less than 0.01% of total meteorite material in ALL collections.
Many people do not appreciate this fact, but think about this:
C-type asteroids comprise about 20% of total population of asteroid belt (may be even more, and Keck proposal says this too).
So, the jeopardy question: how comes that one of the most abundant asteroid type is under-represented in Earth's collections by THREE orders of magnitude?
(correct answer: no way.)
Second:
As I mentioned, there are evidences that CIs do NOT originate from asteroids. One evidence is their chemistry:
it looks like CI chondrites were *cooked* in some kind of brine or fluid (literally, like boiled potatoes :) ).
Which is very difficult (~impossible) to imagine on asteroid. On the other hand, it could happened in cometary core, during close pass to Sun.
There are much more, which I do not want to go in (in part, because I'm not an expert there ;) )
But you can trust me on this one:
It is NOT a good idea to use CI composition as estimate of C-type asteroid.
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Hi again, smoliarm.
What I get from your post is that I just totally screwed up assuming C1 Chondrites represented examples of these carbonaceous asteroids with high volatile content, but you are not specifically saying that those carbonaceous asteroids with some volatile content do not exist.
I really only leapt on this particular class because the Keck paper and the wiki article mentioned about 20% water content, and the wiki article gave the clue that it was not present as ice.
My true aim was to guess how hard it would be to extract the volatiles, and that involved determining what form the water was present in.
So...
Ignoring the C1 Chondrite confusion, what can you say about the presence of volatiles in NEOs such as might be within a small delta-V of our orbit. Any good references we can go and read?
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Hi again, smoliarm.
What I get from your post is that I just totally screwed up assuming C1 Chondrites represented examples of these carbonaceous asteroids with high volatile content, but you are not specifically saying that those carbonaceous asteroids with some volatile content do not exist.
I really only leapt on this particular class because the Keck paper and the wiki article mentioned about 20% water content, and the wiki article gave the clue that it was not present as ice.
My true aim was to guess how hard it would be to extract the volatiles, and that involved determining what form the water was present in.
So...
Ignoring the C1 Chondrite confusion, what can you say about the presence of volatiles in NEOs such as might be within a small delta-V of our orbit. Any good references we can go and read?
Hi, Kelvin,
Well, I would not qualify it as "totally screwed" :) it is pretty common confusion.
Couple remarks:
*** It is better to use term "CI-chondrite", C1 was in use long time ago, and the meaning was different, many meteorites which were classified as C1 some 40 years ago now belong to CM or CO classes.
*** There is no thing like carbonaceous asteroid as a fact. There is a VERY thin hypothesis that some of low-albedo asteroids are similar in composition to carbonaceous chondrites, at least in high abundance of graphite on their surface. It may be true, but may be not.
Spectral data are imprecise for these particular asteroids just because they are LOW-albedo asteroids.
Now the key word - "volatiles".
Speaking of chondrites (any class), there are two volatiles which are easy to extract - sulfur and phosphorus, and they are at % level in abundance. But I guess, they are of little interest here.
Therefore, if you see "significant volatile content" - be careful, it may be not about water at all.
Finally, about chemical form of water in chondrites.
There is no ice in chondrites, for sure. Most likely this is true for any asteroids.
Also, simple hydrated salts (like gypsum) are very rare in chondrites, and hope is not high to find a lot of such hydrates on asteroids.
However, there are phyllosilicates in chondrites, and in some cases these phyllosilicates are indeed the major components. Also, there are some hints, that phyllosilicates occur on low albedo asteroids. You may also see same peculiar words like "serpentine-group minerals, saponite, and chlorite" - there is no need to go into this chemistry.
Because, fortunately, there is a normal human word for all this stuff - CLAY.
But, in chondrites this is not like a wet clay from some river-bed, it is much more like clay in a BRICK, in some wall.
So, your question "how hard it would be to extract the volatiles?" transforms into "how hard it would be to extract the water from a brick?"
It is hard.
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However, there are phyllosilicates in chondrites, and in some cases these phyllosilicates are indeed the major components. Also, there are some hints, that phyllosilicates occur on low albedo asteroids. You may also see same peculiar words like "serpentine-group minerals, saponite, and chlorite" - there is no need to go into this chemistry.
Because, fortunately, there is a normal human word for all this stuff - CLAY.
But, in chondrites this is not like a wet clay from some river-bed, it is much more like clay in a BRICK, in some wall.
So, your question "how hard it would be to extract the volatiles?" transforms into "how hard it would be to extract the water from a brick?"
It is hard.
Well, a fired clay brick water content would depend on temperature it's fired- which can be below 1000 C.
But merely dried clay which hasn't heated over 100 C or hydrated portland cement has a lot of water.
With dry clay, one can crush it into powder and and wet it again to get clay you use to make stuff. Once clay is has been fired, you can not crush into powder and re-use it. What the firing process is doing is removing the water from the clay and silicate is bonding- due the water being removed. And the dry clay shrinks quite a bit after firing. It's structure is changed so water is no longer is absorbed.
Clay in river bottom which dried out, has lots of water in it, but if heated
by geological processes or in a kiln, it's transformed into stone/ceramic material.
Many of the NEOs are from comets, and it's asteroids which now dead comets which seem to me to be the asteroids one could have best chance to mine for water.
NEOs are not permanent. Many of their orbits may be few million to tens millions of years. It is believed that Jupiter perturbs Main belt and cometary bodies further out.
I think it very unlikely small objects [unless newly arrived] could have much water content.
Particular small objects near Earth- whereas small object near Mars could have better chances.
An advantage of small rocks [near Earth or not] is there are so many of them- somewhere around tens of thousands or much more.
Of course we haven't detected a significant amount of them yet, and they would very difficult to simply detect a couple thousand of them.
So it seems that before selecting one, it's unlikely more than a few thousand will be tracked. And because of mission timing and delta-v requirement they will further selected down to dozen or so.
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Oh well, clays don't sound too bad. We had already concluded that if it did contain 20% water, well so does portland cement. Removing water from this sort of material seems to be a common industrial process, it just takes a lot of heating. (there are some links earlier in the thread).
More worrying, there seem to be two camps about the actual amount of water present in any form. I guess we just shouldn't get too carried away with predictions of amounts of water and plans for ISRU, and our first motivation for getting a look at these rocks is to answer these questions.
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Well, a fired clay brick water content would depend on temperature it's fired- which can be below 1000 C.
Chemically, this is only half-true.
The bitter (chemical) truth is: The remaining water content depends on temperature AND TIME.
Just because these rocks were baked for some 4.5 billion years -- even at T well below 500°C -- leaves little hope for theoretical 15% of water in clay minerals. It is a very long time. And it is a very little hope.
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But merely dried clay which hasn't heated over 100 C or hydrated portland cement has a lot of water.
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It's a bad idea to compare portland cement with clays - chemically.
In cements, water present in the form of crystallization water, e.g.:
CaO·2SiO2·3H2O
It is still in the form of *true* water molecules, and it is relatively easy to release.
In clays, it's a different story, not only because the decomposition T is higher, but also because at these temperatures water components in clays tend to react with something else instead of recombining in H2O:
phyllosilica(OH) + troilite + high T -> FeO + SO2 instead of H2O
phyllosilica(OH) + kamasite + high T -> FeO + NiO instead of H2O
phyllosilica(OH) + graphite + high T -> CO + CO2 instead of H2O
et cetera, et cetera...
Yes, heating pure phyllosilicates in a perfectly clean test tube will give you water. But heating of crashed asteroid material will provide you a disappointment - mostly.
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More worrying, there seem to be two camps about the actual amount of water present in any form.
Even worse: there are more than just two camps :)
But, there are some good things, too:
*** we know for sure, that water is present in the Polar regions on the Moon, and hopefully, on a planetary scale. To utilize this water we need water prospecting at specific sites and water mining technology specifically modified for the Moon. Both tasks are real in practical sense.
*** we know for sure, that carbon is abundant (as graphite, or in the form of carbides) in many chondrite classes. We have some hints, that low-albedo asteroids (at least some of them) also have significant amount of carbon. Therefore there is a reasonable hope that low-albedo NEO turns out to have some % of graphite.
*** we know for sure, that carbon in almost any chemical form (excluding diamond) plus water will produce water gas
H2O + C -> H2 + CO
which then can be converted into any kind of hydrocarbons. And the best part here is -- all these reactions are well studied, and all the corresponding catalysts and technologies are developed -- already, nothing to invent, just apply.
So, if we establish lunar mining for ice,
and if we capture a graphite-rich asteroid and transfer it to HLO,
and if we develop a simple and effective transport for ice to HLO
= then we have a Methane/LOX factory in Lunar orbit producing propellant at a small fraction of Earth-produced fuel cost.
However, like my classmate at UMD, Mary, used to say: "Remember Michael, in English *if* is a very long word"
:D
And the final comment, seriously:
IMHO, the road to this wonderful factory starts on the Moon, not on asteroids. So, my hopes are in the Astrobotic - NASA cooperation.
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To be fair, some of the water bearing components in "CI1" (yes, this nomenclature is getting very confusing... :D ) are in similar form to Portland cement.
That is, the phyllosilicates in CI1's appear to consist mainly of two types: iron bearing serpentines and iron bearing saponite (a.k.a. smectite or montmorillonite)
Serpentine: Mg3Si2O5(OH)4
Montmorillonite: (Na,Ca)0.33(Fe,Mg)2Si4O10(OH)2·nH2O
Out of the thousands of meteorites that have been studied, there are only 3 type CI1 chondrites that have been well characterized: Orgueil, Ivuna, and Alais.
Here is one chemical analysis of the Orgueil type CI1 carbonaceous chondrites:
Olivine 7.2 % (by weight)
Troilite 2.1 %
Pyrrhotite 4.5 %
Magnetite 9.7 %
Saponite–serpentine 71.5 %
Ferrihydrite 5.0 %
Evidently, in the Orgueil chondrite the phyllosilicates is mostly serpentine, however. Only the Alais chondrite is predominantly saponite, and even this has a big fraction of serpentine. The Ivuna is unclear: one source say's it's mainly saponite with subordinate serpentine; another says it's largely serpentine interlayered with minor saponitic smectite. Not sure what the "n" factor is in the Alais sample. The Fe:(Fe+Mg) ratio seems to be ~0.4.
Here is my reference:
http://www.planetary.brown.edu/pdfs/4368.pdf
Assuming a meteorioid was 67% smectite, the "n" factor would have to be about 10 H2O in order to provide 20% by mass "easily" accessible H2O. Not sure if that's even chemically possible. I have yet to find an analysis of the water content of the Orgueil, Ivuna, or Alais chondrites.
Also, using spectral data to identify high smectite meteoroids is NOT going to be easy (cf. reference above, page 186)....
Bottom line: I agree that the water content of NEO's is VASTLY oversold; only the psychological explanation of familiophobia can account for this.
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...
Here is one chemical analysis of the Orgueil type CI1 carbonaceous chondrites:
Olivine 7.2 % (by weight)
Troilite 2.1 %
Pyrrhotite 4.5 %
Magnetite 9.7 %
Saponite–serpentine 71.5 %
Ferrihydrite 5.0 %
...
Warren, you quoted MINERAL composition and called it "chemical analysis".
Chemical analysis yields chemical composition (the one which they express in element or oxide percentages).
If you are confusing these two compositions - you are about to make very bad mistake, especially bad with CI-chondrites.
CHEMICAL composition of CIs is very close to the composition of Solar photosphere, and it is generally believed to represent average Solar Nebula composition. Some even believe (including myself) that it is representative for elemental abundances in protoplanetary disc in Early Solar System.
Quite contrary, the MINERAL composition of CIs is absolutely unique, it does not even remotely resemble of any other meteorite type. With respect to saponite, serpentine, and ferrihydrite - you would not find them AT ALL in 99% of any other meteorites.
And, of course, CI's mineral composition is NOT representative for asteroids in the Belt, nor for NEO,
Therefore - do not confuse chemical and mineral compositions.
Out of the thousands of meteorites that have been studied, there are only 3 type CI1 chondrites that have been well characterized: Orgueil, Ivuna, and Alais.
These three are the only CIs large enough for analyses.
There are ONLY six members of CI type out of total ~ 60,000 of documented and classified individual meteorite falls and finds. (If you want to check this total of 60,000 - do not use wiki, they quote John Wasson's numbers, which were correct some forty years ago. Use meteorite catalog by Monica Grady.)
Meteorites originate from asteroid belt - that's what wiki says (and some textbooks). But in fact they they represent the NEO population - that's why they ended up in Earth's collections.
So, if you are in for NEO hunt for asteroid capture, you have 6 / 60,000 chance to get something like CI.
I guess, slim is the right word.
Here are the real chances, approximately:
85% -- ordinary chondrites (like the one which shattered so many windows in Chelyabinsk recently), water content < 0.1%;
5% -- basaltic achondrites (they are indeed pretty much basalt-like, at least in water content, dry as ash);
9% -- iron and stony-iron meteorites. These are pretty simple in mineralogy: kamasite and taenite (Fe-Ni allows), troilite, schreibersite, and olivine (in stony-irons). No water at all.
And finally, about 1 % -- carbonaceous chondrites, which are the only ones to have significant carbon content, and therefore can be used for ISRU. One percet is not a lot, but it is still 100 times higher than 0.01%.
PS: the correct name for Ivuna-type is just "CI". There is no "type CI1 chondrites". CI1 is used for particular meteorite to show its type and metamorphic group (although all CIs belong to group 1).
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So, if you are in for NEO hunt for asteroid capture, you have 6 / 60,000 chance to get something like CI.
I guess, slim is the right word.
I wish my Russian were anywhere near as good as your English.
You may already know this, but "fat chance" and "slim chance" mean about the same thing. Ain't English great?
Thanks for your asteroid lessons. We all appreciate them.
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Well, a fired clay brick water content would depend on temperature it's fired- which can be below 1000 C.
Chemically, this is only half-true.
The bitter (chemical) truth is: The remaining water content depends on temperature AND TIME.
Just because these rocks were baked for some 4.5 billion years -- even at T well below 500°C -- leaves little hope for theoretical 15% of water in clay minerals. It is a very long time. And it is a very little hope.
But merely dried clay which hasn't heated over 100 C or hydrated portland cement has a lot of water.
It's a bad idea to compare portland cement with clays - chemically.
In cements, water present in the form of crystallization water, e.g.:
CaO·2SiO2·3H2O
It is still in the form of *true* water molecules, and it is relatively easy to release.
In clays, it's a different story, not only because the decomposition T is higher, but also because at these temperatures water components in clays tend to react with something else instead of recombining in H2O:
phyllosilica(OH) + troilite + high T -> FeO + SO2 instead of H2O
phyllosilica(OH) + kamasite + high T -> FeO + NiO instead of H2O
phyllosilica(OH) + graphite + high T -> CO + CO2 instead of H2O
et cetera, et cetera...
Yes, heating pure phyllosilicates in a perfectly clean test tube will give you water. But heating of crashed asteroid material will provide you a disappointment - mostly.
That's interesting. Thanks.
But getting SO2 or CO2 is not bad.
When mining water, what one mainly doing is getting Oxygen. Oxygen is in everything, but water is relativity easy way to get O2.
O2 will probably start off and become quite cheap, but in terms of mass it's what is needed most for rocket fuel.
As guess, hydrogen per mass would probably be about 4 or more times more expensive than oxygen.
So if oxygen was $500 per lb, and hydrogen is $2000 per lb. For fuel rich mixture [used in rockets] you have 6 lb oxygen and 1 lb of Hydrogen. So
at above prices: $3000 of oxygen and $2000 hydrogen give 7 lbs of rocket- $714.29 per lb of rocket fuel.
One thing about the "hydrogen economy" in space is one gets good value for the Oxygen [it's needed the most- and it nearly free on Earth].
So on Earth if split water what considers as valuable is the H2, but in space you get as much or more for the oxygen produced.
It seems eventually since there so much oxygen [40% mass of surface of Moon [or any body] is oxygen, and if mining metals on large scale [get metals- iron, aluminum. titanium, etc] oxygen will be a common byproduct- so over enough time, oxygen will get very cheap, but near term [decades from start mining in space] oxygen will have one of highest value [due to highest demand].
So anyhow, CO2 would valuable as one would combine with hydrogen and get O2 and methane.
And with SO2 in beginning you be mostly interested in it's O2.
Though as recall there are sulfur rockets. Hmm. Need zinc.
Anyhow some people have thought mining sulfur could useful for some kind of rocket propellent. And sulfur is generally useful in many ways.
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And finally, about 1 % -- carbonaceous chondrites, which are the only ones to have significant carbon content, and therefore can be used for ISRU. One percet is not a lot, but it is still 100 times higher than 0.01%.
All the more need for a VASIMR that can run on LOX.
Then most asteroids can be used for ISRU.
By the way, what about Phobos and Deimos? Do they have water?
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...
Here is one chemical analysis of the Orgueil type CI1 carbonaceous chondrites:
Olivine 7.2 % (by weight)
Troilite 2.1 %
Pyrrhotite 4.5 %
Magnetite 9.7 %
Saponite–serpentine 71.5 %
Ferrihydrite 5.0 %
...
Warren, you quoted MINERAL composition and called it "chemical analysis". do not confuse chemical and mineral compositions.
OK, OK: I admit I flunked mineralogy class; luckily they let me substitute primate ecology for the requirement so I never had to retake it.... ;)
There are ONLY six members of CI type out of total ~ 60,000 of documented and classified individual meteorite falls and finds. So, if you are in for NEO hunt for asteroid capture, you have 6 / 60,000 chance to get something like CI.
I guess, slim is the right word.[/quote]
Well, to be fair, there is probably some strong sampling bias going. My understanding is that (a) CI meteors tend to get blown to smithereens when they hit the atmosphere, and (b) CI meteorites don't hold up well to Earth weathering even if they survive the impact.
And finally, about 1 % -- carbonaceous chondrites, which are the only ones to have significant carbon content, and therefore can be used for ISRU
But most of the asteroid mining hype states that their target is water, which entails that they'll want to go after saponite enriched CI meteoroids. Thus if all CC's are 1% of the total population of NEA's, then CI's are going to be more like 0.1%--still a lot better than 0.01%, but "slim" chances nevertheless.
PS: the correct name for Ivuna-type is just "CI". There is no "type CI1 chondrites". CI1 is used for particular meteorite to show its type and metamorphic group (although all CIs belong to group 1).
Well, if we really want to get technical ( :P ) isn't it the case that "CI" refers to the "class" of meteorite, and the "1" refers to its petrological "type"? Also, according to some references, it's possible that CI's can grade into petrological type 2, whatever that is, and thus one could technically have CI2 meteorites, although the few that have actually been studied have all been CI1's....
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By the way, what about Phobos and Deimos? Do they have water?
Surface spectra according to the oracle does not show evidence for hydrated minerals, apparently. It does speculate that there might be water trapped in the interior. This is hard to believe IMO, since Phobos is on the wrong side of the so-called ice-line (the region of the solar system where it's generally cold enough for water ice to be stable in a vacuum), and if there was a lot of water in the interior, we should see evidence of it in terms of hydrated minerals on the surface.
However, the oracle also says Phobos has an axial tilt of 0 degrees, so you could possibly get permanently shaded craters in the polar regions like you find on the Moon or Mercury, and these should contain relatively abundant water ice. Not sure if there is any direct spectral evidence to confirm this hypothesis....
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On Phobos & Deimos composition:
Believe it or not, we do know chemical and mineral composition of Phobos quite well, because we have sample in hand. Yes, with Phobos-Grunt failed, nevertheless, we have 2.5 lbs of Phobos material, as meteorite called KAIDUN.
This meteorite fell some 35 years ago in Yemen right on the territory of Soviet military base, it was lucky from the very beginning. Because nobody believed it was natural, they thought it was a failed NATO missile or, worse, some spy device. Therefore, it was collected, preserved, and studied in best possible way with huge federal funding. Seriously, it was transferred to Moscow within hours of impact via urgently dispatched supersonic jet (the only case in the entire history of Russian meteorite studies).
It was preliminary classified as “very strange chondrite”. Which was lucky again – the officials concluded it was a spy thing developed by CIA and smartly disguised by NASA as an innocent meteorite. See, it fell too close to some object X, which never was in Yemen, moreover, Soviet Union never produced it. So, the funding for studying did not cease but tripled, and the rock was investigated millimeter by millimeter literally, with best instruments available. (This is a true story from the first hand – the PI for Kaidun study was A.V.Ivanov, and I was his grad student only 5 years later). No CIA microchips nor cameras were found, but Kaidun become the best studied meteorite in Russian collections. And it still keeps this record, lucky guy.
Later, it was classified as “very strange carbonaceous chondrite”, and finally, as “very strange CR chondrite”.
Now, the main part:
In 2003, at Lunar Conference in Houston, Andrei Ivanov and Michael Zolensky suggested their explanation for strange nature of Kaidun:
http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1236.pdf (two last paragraphs in the abstract)
They concluded that it originates from the closest Mars moon, Phobos. I was there, in the conference room, and I can tell you that the general reaction was severe skepticism plus some fierce (and loud) sarcasm. I proudly note that I was not among critics; I liked the idea from the beginning. Not because Andrei was my dissertation advisor, I just liked the idea, although at the time it did sound crazy.
In following 10 years this "crazy" idea got several confirmations from different sides independently. The very last confirming data came just months ago – from Curiosity, and they are strong enough for me to call it "proof".
It is an interesting chain of reasoning (I mean, how they concluded that Kaidun = Phobos), but it is far from this thread, so I just go to
COMPOSITION OF PHOBOS.
FIRST, it has low density. It is so low, that some people suggested it is not a rock, but some artificial object (alien ship). Well, unfortunately it is not. Then, it was suggested, that low density of Phobos is due to large water ice core. Data from MRO and Mars Express do NOT confirm this, spectral results of all types in good agreement show no water ice, no crystallization water, not any traces of OH-groups on Phobos surface. In full agreement, Kaidun data strongly suggest that Phobos is very dry – on the surface AND below. (In Kaidun papers you can see phyllosilicates frequently mentioned – trust me, these are minor amounts). Low density of Phobos is most likely due to high porosity (micro-porosity), which is in good agreement with recent data on outer (captured) Jupiter moons. So, most likely Phobos has no water in any form, although you can read the opposite, especially in old articles - disregard these.
SECOND thing, which is also sad: Among all carbonaceous chondrites, CR-chondrites are on the very low end in carbon content (graphite is accessory mineral in CRs). So, Phobos is an unlikely source for carbon too.
THIRD, Kaidun consists mainly of chondrules (65-70% by volume) – little molten droplets of primordial matter in Solar Nebula, which were formed by high voltage discharges (static or electromagnetic) in protoplanetary disc, and these discharges were high-T too, at least 1500 K. So that these guys, chondrules, are depleted in everything, which boils below.
FINALLY, mining expectations for volatiles on Phobos are close to zero. But, maybe it’s a good place to look for iridium, ruthenium, or tungsten, who knows.
Now,
COMPOSITION OF DEIMOS:
We have no Deimos samples (yet), but we do have pretty good spectral data. They are actually the best in reproducibility, as I heard. They do show small water lines, too low for practical extraction, although hope remains for higher water content below surface. The good thing, there are some distinct carbon spectral lines, so there is a good chance for significant graphite in Deimos regolith.
As whole, spectral data place Deimos really close in composition to major carbonaceous chondrite types, CM and CO, with better confidence than typically for asteroids.
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They concluded that it originates from the closest Mars moon, Phobos. I was there, in the conference room, and I can tell you that the general reaction was severe skepticism plus some fierce (and loud) sarcasm. I proudly note that I was not among critics; I liked the idea from the beginning. Not because Andrei was my dissertation advisor, I just liked the idea, although at the time it did sound crazy.
So did you like the idea because of evidence others missed or because it would be cool. Liking an idea because of wishful thinking without evidence if nothing to be proud of even if it does turn out to be right.
Of course neither should one dismiss an idea just because it sounds crazy, if the evidence back it up.
Anyway, very cool story. That is indeed one lucky meteorite.
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...the officials concluded it was a spy thing developed by CIA and smartly disguised by NASA as an innocent meteorite.
Our guys are pretty darn good, eh? You all missed the invisible one that they dropped only 100m away!
But what a great story! Thanks for sharing.
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...
OK, OK: I admit I flunked mineralogy class;
I did not. There were two reasons - we had very good professor and very mean assistant. She was so mean, the girls in our class called her "Triple-W". I am afraid it was not for "world wide web" but for "Wicked Witch of the West".
Oh, I forgot, there was third reason - I had no chance for substitution :) Grant would pay for one take only...
Well, to be fair, there is probably some strong sampling bias going. My understanding is that (a) CI meteors tend to get blown to smithereens when they hit the atmosphere, and (b) CI meteorites don't hold up well to Earth weathering even if they survive the impact.
I do not think the bias can be really strong, and I'm sure it works IN FAVOR of CIs. Here is why:
We know for sure there is a strong bias in number of meteorites in favor of iron meteorites, and we believe it is because of:
1. Irons have much higher density (which translates into wider corridor for "surviving trajectory");
2. They are more robust, which results in larger final pieces (more prominent)
3. Last but not the least - irons are easy to spot and easy to discern from terrestrial rocks -- unlike say basaltic achndrite which looks exactly like normal basalt.
So, lets compare CIs with all other chondrites:
1. They are on the high end of density range, although the difference is much less than with irons
2. Same picture - they are more robust than ordinary chondrites, but not by much.
3. Again, the same - CIs are strange looking rocks, they do stand out in many common rocky plains.
Well, if we really want to get technical ( :P ) isn't it the case that "CI" refers to the "class" of meteorite, and the "1" refers to its petrological "type"? Also, according to some references, it's possible that CI's can grade into petrological type 2, whatever that is, and thus one could technically have CI2 meteorites, although the few that have actually been studied have all been CI1's....
My classmate, Mary, claimed there is a proverb in Spanish, something like this:
** You may call me "Frying Pan" if you like, just do not put me on the stove-top **
but there is a chance she made it up :) (she has a record of making up funny stuff)
So, yes, I agree.
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They concluded that it originates from the closest Mars moon, Phobos. I was there, in the conference room, and I can tell you that the general reaction was severe skepticism plus some fierce (and loud) sarcasm. I proudly note that I was not among critics; I liked the idea from the beginning. Not because Andrei was my dissertation advisor, I just liked the idea, although at the time it did sound crazy.
So did you like the idea because of evidence others missed or because it would be cool. Liking an idea because of wishful thinking without evidence if nothing to be proud of even if it does turn out to be right.
Of course neither should one dismiss an idea just because it sounds crazy, if the evidence back it up.
Anyway, very cool story. That is indeed one lucky meteorite.
I am a chemist, with some background in meteoritic mineralogy and petrology. Therefore, it was very convincing for me that crazy idea of Andrei and Michael explained all the chemical and petrological peculiarities of Kaidun very neatly, with very strict and simple logic.
And I'm glad you liked the story :)
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...the officials concluded it was a spy thing developed by CIA and smartly disguised by NASA as an innocent meteorite.
Our guys are pretty darn good, eh? You all missed the invisible one that they dropped only 100m away!
But what a great story! Thanks for sharing.
Well, the guys are good indeed, no doubt :) BUT, Russian generals - they did NOT miss the "invisible one" ;D
It's me - I shortened the story, I confined myself to solid facts.
But there is a gossip part:
When Russian generals learned that Kaidun is a "strange meteorite", but it does not have any embedded electronics, they concluded that Americans used it as a diversion, and during the loud and fiery "meteorite" descent they somehow quietly planted something really small. Now, this "object X" was like 2 or 3 square miles of desert in the middle of nowhere with pretty much nothing of the surface, everything was underground. So, they ordered like battalion of KGB officers, and these poor guys SIEVED all the sand on TWO square miles of desert, in the heat of Yemen summer, two times. They used 100-mesh sieves, reportedly.
But that's a gossip, Andrei was not there, he was in Moscow, analyzing Kaidun.
And thanks, I'm glad you liked this story :)
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I would say in general terms whether space rocks have minable water
is more difficult to determine than whether the Moon has minable water.
Mining water in space would very important in terms of our future and that
determining where there is minable water is something NASA should have
as high priority.
It seems to me, in terms total volumes of potential available water there is
more water in NEOs than on Moon. And in terms all rocks in space [all stuff smaller then 500 km in diameter] they have more water than Earth- and most of these rocks and this water is beyond Jupiter.
Mars has lots of water in terms the amount that is minable at some point in future- but Mars is a very, very dry world as compared to Earth.
The Moon has far less water than Mars, but it seems to me, the Moon has best chance in terms nearest future of finding minable water as compared to Mars or space rocks.
The dirt in your backyard [if you have one] could have more water, than a future site found on the Moon which is considered to be minable and is actually mined.
If you had a backyard which was 1 km square and it had swimming pool, it possible that a 1 km square location on the Moon has more water which can be mined.
It's also possible that if your 1 km square backyard was a desert, this could have more water than the best location on the Moon- and the Moon still has minable water.
So it's possible that earth desert conditions which have no well water available, is minable on the Moon.
And areas on Mars similar to a meters of frozen permafrost- or frozen swamp- having far more water than such desert backyard, which is not minable [in near term].
Or said different way, the reason we are NOT currently mining lunar water, is probably due NASA failing to explore the Moon to determine if and where there is minable water.
Whereas it's less likely that if NASA had thoroughly explored numerous space rocks and/or Mars whether we already be mining this water.
The issue of mining water in space is [IMO] about making rocket fuel.
Getting water so you wash your clothes and do the dishes is not what
I talking about in terms of minable water. It's good that some crew on some base can get water at their location, but it's not as significant in terms the future of humans living on Earth.
If people living in Antarctic can get water at their location, rather shipping the water to the location it could be a important economic issue regarding this research station but has little to do with the future of humankind.
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http://www.youtube.com/watch?v=g4OBUupicWg
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So, they ordered like battalion of KGB officers, and these poor guys SIEVED all the sand on TWO square miles of desert, in the heat of Yemen summer, two times...
The story gets better and better!
Are you saying that they combed the desert????
Dang. Hernalt beat me to it!
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@ smoliarm: the Kaidun meteorite story is fascinating. You should write it up as an article for the Space Review!
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So, they ordered like battalion of KGB officers, and these poor guys SIEVED all the sand on TWO square miles of desert, in the heat of Yemen summer, two times...
The story gets better and better!
Are you saying that they combed the desert????
Yes, but not with combs. They used sieves, like this one
(http://www.labmart.com/images/sieves/759003.jpg)
And they did not just comb the surface, they had to do it TWO feet deep, for TWO square miles.
@ smoliarm: the Kaidun meteorite story is fascinating. You should write it up as an article for the Space Review!
Thanks :)
May be, I'll talk Andrei into it, it's his story after all, and he has more funny details about it.
For now, I leave it as NSF exclusive ;)
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And they did not just comb the surface, they had to do it TWO feet deep, for TWO square miles.
So you're saying, in the *cough* SpaceBalls *cough* documentary, those guys were complaining too much for combing the desert? From the screeen shot offered by my "esteemed colleague" (and I use the term loosely) they only went to a depth of six inches.
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And they did not just comb the surface, they had to do it TWO feet deep, for TWO square miles.
So you're saying, in the *cough* SpaceBalls *cough* documentary, those guys were complaining too much for combing the desert?
...
Yes, this follows from the Second Consequence of Forth Law of Thermodynamics:
"Any given system in any given process has an option to go for worse."
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On Phobos & Deimos composition:
...
Thanks for that too, smoliarm :)
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And they did not just comb the surface, they had to do it TWO feet deep, for TWO square miles.
That's one and a half million cubic meters. At ten liters a second it would take five years. :o
How many people were working on than combing? What kind of machinery did they have to help.
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And they did not just comb the surface, they had to do it TWO feet deep, for TWO square miles.
That's one and a half million cubic meters. At ten liters a second it would take five years. :o
Well, for 2 sq. miles x 2 feet deep I got 3 million cubic meters. And, the original tale says that KGB guys did it twice, so it's more like 6 million m3, but who cares? -- I told it's a gossip, and gossip does not have to be verisimilar - by definition...
How many people were working on than combing? What kind of machinery did they have to help.
It is highly classified, how would I know? :D