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#20 by Warren Platts on 28 Apr, 2013 14:32
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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) -
#21 by smoliarm on 28 Apr, 2013 18:48
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With respect to their estimate of C-asteroid composition -- NO.
Smoliarm: Do you agree with the Keck assessment?
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.Quote from: JohnFornaroQuote 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.
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:QuoteA 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)...
never.
...Carbonaceous asteroid material similar to the CI chondrites is easy to ...
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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#22 by smoliarm on 28 Apr, 2013 19:38
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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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#23 by KelvinZero on 28 Apr, 2013 19:55
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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? -
#24 by smoliarm on 28 Apr, 2013 21:31
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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. -
#25 by gbaikie on 29 Apr, 2013 00:05
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Quote
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. -
#26 by KelvinZero on 29 Apr, 2013 08:35
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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. -
#27 by smoliarm on 29 Apr, 2013 11:03
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Chemically, this is only half-true.
Well, a fired clay brick water content would depend on temperature it's fired- which can be below 1000 C.
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.
[/quote]
But merely dried clay which hasn't heated over 100 C or hydrated portland cement has a lot of water.
[/quote]
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. -
#28 by smoliarm on 29 Apr, 2013 12:16
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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"
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. -
#29 by Warren Platts on 29 Apr, 2013 13:58
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To be fair, some of the water bearing components in "CI1" (yes, this nomenclature is getting very confusing... ) 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. -
#30 by smoliarm on 29 Apr, 2013 20:13
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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.QuoteOut 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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#31 by JohnFornaro on 30 Apr, 2013 00:05
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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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#32 by gbaikie on 30 Apr, 2013 06:27
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Quote
Well, a fired clay brick water content would depend on temperature it's fired- which can be below 1000 C.
QuoteChemically, 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.QuoteBut merely dried clay which hasn't heated over 100 C or hydrated portland cement has a lot of water.
QuoteIt'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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#33 by alexterrell on 30 Apr, 2013 06:52
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All the more need for a VASIMR that can run on LOX.
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%.
Then most asteroids can be used for ISRU.
By the way, what about Phobos and Deimos? Do they have water? -
#34 by Warren Platts on 30 Apr, 2013 13:10
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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.Quote from: smoliarmAnd 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.Quote from: smoliarmPS: 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 (
) 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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#35 by Warren Platts on 30 Apr, 2013 13:16
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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.... -
#36 by smoliarm on 30 Apr, 2013 15:49
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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. -
#37 by Tass on 30 Apr, 2013 16:09
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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. -
#38 by JohnFornaro on 30 Apr, 2013 16:34
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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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#39 by smoliarm on 30 Apr, 2013 18:53
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...
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".
OK, OK: I admit I flunked mineralogy class;
Oh, I forgot, there was third reason - I had no chance for substitution Grant would pay for one take only...QuoteWell, 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.QuoteWell, if we really want to get technical (
) 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.
)
) 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....