[meteorite-list] Cold Asteroids May Have ASoftHeart(AllendeMeteorite)
From: Richard Montgomery <rickmont_at_meteoritecentral.com>
Date: Sat, 16 Apr 2011 19:43:28 -0700 Message-ID: <86213246AF6143F3AB5CEC7C7123C4D5_at_bosoheadPC> Okay, List, ready for another neophyte question? Here goes: Looking FROM space to the Earth, does the absorption spectra of our planet in the 3-micron band (water) measure proportionate, i.e. zero in that band, which would relegate much of what is seen of US to be non-reflective? Do such measurements exist? Curious Richard Montgomery ----- Original Message ----- From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net> To: <lebofsky at lpl.arizona.edu> Cc: "metlist" <meteorite-list at meteoritecentral.com>; "MEM" <mstreman53 at yahoo.com> Sent: Saturday, April 16, 2011 1:31 PM Subject: Re: [meteorite-list] Cold Asteroids May Have ASoftHeart(AllendeMeteorite) > Hi, Larry, List, > > As usual, I grabbed an idea and ran off the cliff > with it; now Larry has handed me the anvil, just > like I was the well-known cartoon Coyote. And also, > as usual, Larry is right. Must be gratifying, having > someone who has to keep posting that you are right, > Larry... > > Larry said >> The presence of hydrated silicates on asteroid >> 2 Pallas dates back to the early 1980s > > Larry is referring modestly to: > Feierberg, M. A.; Larson, H. P.; LEBOFSKY, L. A. (1982). > "The 3 Micron Spectrum of Asteroid 2 Pallas.". > Bulletin of the American Astronomical Society 14: 719. > Unfortunately, the ADS system only gives the page with > the title at the bottom of the page and then cuts off the > article which starts on the next page... > > Although, in my defense, I could cite: > http://www.lpi.usra.edu/books/AsteroidsIII/pdf/3031.pdf > in which there is a table that shows Pallas (B-class) > with ZERO absorption in the 3-micron band (water, > in other words). Also has "Lebofsky, L. A." as an author. > > Links to all or part of Larry's 304 articles: > http://adsabs.harvard.edu/cgi-bin/nph-abs_connect?return_req=no_params&author=Lebofsky,%20L.%20A.&db_key=AST > > Looking for water (or anything like it) by peering through > the wet sodden atmosphere of Earth is a chancy business; > the data needs to massaged. I'm not suggesting that the > data isn't reliable, just that it's likely to have fuzzy edges. > > Just an abstract, but summarizes well: > http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WGF-4731CCX-DV&_user=10&_coverDate=12%2F31%2F1983&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1720558577&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b3a90d3f66329ead2085b10dd7dbde6b&searchtype=a > "High resolution spectroscopic observations of > asteroid 2 Pallas from 1.7-3.5 ?m are reported. > These data are combined with previous measurements > from 0.4-1.7 ?m to interpret Pallas' surface mineralogy. > Evidence is found for low-Fe-2+ hydrated silicates, > opaque components, and low-Fe-2+ anhydrous silicates. > This assemblage is very similar to carbonaceous chondrite > matrix material such as is found in type CI and CM > meteorites, but it has been subjected to substantial > aqueous alteration and there is a major extraneous > anhydrous silicate component. This composition is > compared to that of asteroid 1 Ceres. Although there > are substantial differences in their broad band spectral > reflectances, it appears that both asteroids are genetically > related to known carbonaceous chondrites." > > These folks thinks it's drier than Larry's studies: > Sato, Kimiyasu; Miyamoto, Masamichi; Zolensky, Michael E. > (1997). "Absorption bands near 3 m in diffuse reflectance > spectra of carbonaceous chondrites: Comparison with asteroids" > http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1997M%26PS...32..503S&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf > > More new looks. These guys think Pallas is smaller > than previously thought, they say, and they have refined > that strange shape (very nice graphics): > http://www.eso.org/sci/activities/santiago/projects/PlanetaryGroup/journal_club/slides/ESO.JournalClub-2007.08.14-BenoitCARRY.pdf > And if it were smaller but the mass is correct, then Pallas' > density would be higher. That would have implications > for trying to mentally reconstruct it... > > And of course in Larry's second reference, Pallas is > bigger than we thought and hence less dense. This > suggests we have a way to go in order to pin this down. > > It should be explained (if anybody is still following this) > that Pallas is not easy to observe -- it dark and its > eccentric orbit carries it far enough away to be very > dim except at those short intervals when it's close to > the Sun and the Earth passes it at its nearest approach. > > Is there a general trend toward our perceiving primitive > meteorites as drier than we thought?. See: > "Primitive Meteorites Depleted in Volatiles "(press release) > quotes from Phil Bland and Monica Grady: > http://www.pparc.ac.uk/Nw/meteorite.asp > > Obviously, Pallas is not "dry" in the same sense as the > Moon or Mercury and I was wrong to imply that, > although it might be less than 10%. The Sato paper > suggests it's more like Renazzo than like Larry's > suggestion of Murchison, or about half as "wet." > 5%? > > There's no substitution for actually going there and > looking it over for yourself, which someday we'll be > able to. Until then, we'll have to have fun guessing > and peeking through the wet murk of Earth. > > > > Sterling K. Webb > --------------------------------------------------------------------------------- > ----- Original Message ----- > From: <lebofsky at lpl.arizona.edu> > To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net> > Cc: "metlist" <meteorite-list at meteoritecentral.com>; "MEM" > <mstreman53 at yahoo.com> > Sent: Saturday, April 16, 2011 11:27 AM > Subject: Re: [meteorite-list] Cold Asteroids May Have A > SoftHeart(AllendeMeteorite) > > > > Hi Sterling > > Sorry for taking so long in responding, but I am still catching up from > being out of email access for three days this weekend and I missed this > one. > > The presence of hydrated silicates on asteroid 2 Pallas dates back to the > early 1980s and has been confirmed numerous times and spectrally matches > Murchison. > > So unless you imply low water as being only about 10% water by mass, > Pallas is not dry! > > Larry > > http://www.lpi.usra.edu/meetings/LPSC98/pdf/1310.pdf > > http://adsabs.harvard.edu/abs/2008DPS....40.2204S > >>> It shows signs of olive and pyroxene, >> >> I meant OLIVINE, of course. >> >>> when we got their... >> >> and THERE. Spell checkers don't catch >> these mistakes, only working brains, so... >> New rule: No more Posts after midnight. >> >> >> Sterling K. Webb >> --------------------------------------------------------- >> ----- Original Message ----- >> From: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net> >> To: "MEM" <mstreman53 at yahoo.com>; "Richard Montgomery" >> <rickmont at earthlink.net>; "metlist" >> <meteorite-list at meteoritecentral.com> >> Sent: Thursday, April 14, 2011 1:21 AM >> Subject: Re: [meteorite-list] Cold Asteroids May Have A >> SoftHeart(AllendeMeteorite) >> >> >> Hi, >> >> Way too much stuff here to deal with all, >> but I have a word about 2 Pallas as a >> "Carbonaceous parent body." >> >> Pallas has a silicate spectrum. A great many >> bodies do. It shows signs of olive and pyroxene, >> with low iron and water. If it resembles any >> Carbonaceous chondrite, it's a CR with no >> hydrated minerals or very little. >> >> Pallas is very dark, with an albedo of 12%-14%, >> almost as dark as our moon, whose albedo is >> 7% to 8%. Yes, when we look at the Moon >> at night, it looks BRIGHT, but in reality, the >> Moon is about the color and reflectivity of >> a huge lump of black anthracite coal. >> >> The fact that it doesn't look like a lump of coal >> in pictures taken on the Moon or looked to the >> astronauts as a very light grey demonstrates >> the ability of the human mind to scale image >> intensity to the Earth norm and to expose film >> to achieve similar results. >> >> Pallas is a little brighter than the Moon but >> some darker than Mercury which is about 15% >> to 16% albedo. Of course, if a human eye was ON >> Mercury, the planet would appear to us as blazing >> white under sunlight more than 2.5 times brighter >> than here at Earth. >> >> The density of Pallas is about 2.8. The similar >> sized Vesta is 3.43, our Moon 3.35, Mercury . For >> comparison, Earth's crustal rocks, mostly silicates, >> have a mean density of about 3.0. It seems unlikely >> that Pallas has an iron core. Like the Moon and >> Mercury, it seems to be essentially waterless. >> >> The spectral "classifications," both the Tholin and >> the 2Mass, classify a great many asteroids as varieties >> of "Carbonaceous," but we see far fewer Carbonaceous >> meteorites than they see asteroids! >> >> We spent many decades trying to analyze the surface >> of the Moon spectroscopically, it being so conveniently >> close and all, but none of it told us that much about >> what we'd find when we got their. Similarly, spectral >> studies of Mars from Earth are largely forgotten for >> the same reason: they were wrong. >> >> I expect Pallas to be excessively dry and waterless, >> made of excessively dark rock, primitive in composition, >> likely has little plagioclase on the surface, probably >> isn't "differentiated" and lacks basalt melts. But hey! >> I'm just guessing. >> >> There is a chance that we may get a look at Pallas. >> When the Dawn mission is mission is finished at Ceres, >> if all systems are functioning and fuel supplies are >> within parameters, it COULD be sent on a flyby of >> Pallas. Dawn couldn't orbit it, but it could grab a lot >> of lovely snapshots on that pass. >> >> Of course, we'd have to get it funded by Congress... >> >> Groan. >> >> >> >> Sterling K. Webb >> -------------------------------------------------------------------------- >> ----- Original Message ----- >> From: "MEM" <mstreman53 at yahoo.com> >> To: "Richard Montgomery" <rickmont at earthlink.net>; "metlist" >> <meteorite-list at meteoritecentral.com> >> Sent: Wednesday, April 13, 2011 9:31 PM >> Subject: Re: [meteorite-list] Cold Asteroids May Have A Soft >> Heart(AllendeMeteorite) >> >> >>> Let me play politician and ask to "revise and extend my remarks". >>> There are >>> asteroid gurus on the list who are more likely able to address this >>> and I'd like >>> to hear from them. Your theory/question is partially in the right >>> direction so >>> let me re-frame it. I believe we have "likely" detected all the >>> existent >>> asteroids in our inner solar system which are large enough to have >>> formed >>> basalt/cores--aka differentiated. That size is hard >>> overlook(100-300km >>> minimum?). I read somewhere that as many as 12-20 major/minor planets >>> would >>> have formed in the early solar system that are no longer with us as >>> major/minor >>> intact bodies.( i.e. absorbed or ejected) >>> >>> As to meteorite parent bodies, what we have yet to inventory and, for >>> which we >>> have not had a specimen drop by Earth for comparison, are these long >>> ago >>> disrupted bodies. These bodies which now are represented only by >>> minor, >>> irregular, slivers, slices, and rubble piles within certain swarms of >>> asteroids >>> in different sectors of the solar system. >>> >>> There is a "diogenite-like" spectrum coming from an outer-belt >>> asteroid whose >>> orbit proves it cannot be related to Vesta. I mentioned the caveat >>> that there >>> may be some remnants of asteroids which were differentiated in the >>> early solar >>> system and for whatever reason are no longer in tact. We may only >>> have a >>> fraction of the original large body such that while we have located >>> all the >>> differentiated intact ergo larger asteroids, we may need to be >>> looking for >>> shards of former bodies to match meteorites from our collections. The >>> reason >>> all our "HED"s are from Vesta is probably that Vesta is on our "mail >>> route" and >>> quantum transport from Vesta to Earth is a favorable happenstance. >>> >>> "1459 Magnya: Orbits in the outer main belt, too far from Vesta to be >>> genetically related. May be the remains of a different ancient >>> differentiated >>> body that was shattered long ago." Spectrum is diogenite-like >>> >>> Another candidate which may be the source of olivine-diogenites but is >>> a chunk >>> off Vesta: >>> "2579 Spartacus - contains a significant portion of olivine, which may >>> indicate >>> origin deeper within Vesta than other V-types." >>> See list at: >>> <http://en.wikipedia.org/wiki/V-type_asteroid> >>> <http://en.wikipedia.org/wiki/4_Vesta> >>> >>> Pallas and its family of asteroids is certainly a candidate for one of >>> the >>> Carbonaceous parent body, even thought it shows no major excavations. >>> "2 Pallas is a large and most certainly differentiated body but lacks >>> evidence >>> of a deep >>> excavation and its spectrum shows carbonaceous chondrite affinities. >>> However >>> 75% of the astrtoids out there whose spectra we've measured fall in >>> the C or >>> Carbonaceous class." >>> <http://en.wikipedia.org/wiki/2_Pallas> >>> <http://en.wikipedia.org/wiki/Carbonaceous_chondrite> >>> Also in my reading there is good indication that the Martian moons are >>> captured >>> carbonaceous asteroids >>> <http://en.wikipedia.org/wiki/Moons_of_Mars> >>> >>> Asteroid types More than I can retain in my head: >>> <http://nineplanets.org/asteroids.html> >>> <http://en.wikipedia.org/wiki/Asteroid_spectral_types> >>> * C-type, includes more than 75% of known asteroids: extremely >>> dark >>> (albedo 0.03); similar to carbonaceous chondrite meteorites; >>> approximately the same chemical composition as the Sun minus hydrogen, >>> helium >>> and other volatiles; >>> >>> * S-type, 17%: relatively bright (albedo .10-.22); metallic >>> nickel-iron >>> mixed with iron- and magnesium-silicates; >>> >>> * M-type, most of the rest: bright (albedo .10-.18); pure >>> nickel-iron. >>> * There are also a dozen or so other rare types. >>> >>> Read more about Asteroids l Asteroid facts, pictures and information >>> by >>> nineplanets.org * C-type, includes more than 75% of known asteroids: >>> extremely dark (albedo 0.03); similar to carbonaceous chondrite >>> meteorites; approximately the same chemical composition as the >>> Sun minus >>> hydrogen, helium and other volatiles; >>> >>> * S-type, 17%: relatively bright (albedo .10-.22); metallic >>> nickel-iron >>> mixed with iron- and magnesium-silicates; >>> >>> * M-type, most of the rest: bright (albedo .10-.18); pure >>> nickel-iron. >>> * There are also a dozen or so other rare types. >>> >>> Read more about Asteroids l Asteroid facts, pictures and information >>> by >>> nineplanets.org >>> >>> Meteorites and their Parent Bodies 2nd Edition. Harry Mc Sween which I >>> think us >>> a google book online. >>> >>> Elton >>> >>> >>> >>> ----- Original Message ---- >>>> From: Richard Montgomery <rickmont at earthlink.net> >>>> To: Ron Baalke <baalke at zagami.jpl.nasa.gov>; Meteorite Mailing List >>>><meteorite-list at meteoritecentral.com> >>>> Sent: Wed, April 13, 2011 8:39:46 PM >>>> Subject: Re: [meteorite-list] Cold Asteroids May Have A Soft Heart >>>>(AllendeMeteorite) >>>> >>>> Ron and List, >>>> >>>> This new evidence fits exactly into the recent question I posted, >>>> 'Vesta, >>>> for sure?' >>>> >>>> I only heard back from Elton (thanks, sincerely!) and yet now with >>>> this >>>> hypothesis, my question lingers as to the absolute recognition of >>>> parent >>>> bodies, with my query as to the yet-undiscovered potential pairings >>>> of >>>> undiscovered asteroids. >>>> >>>> MEM pointed out that the largest asteroids (aka Vesta etal) have >>>> already >>>> been located, with tell-tale impact and reflective signatures that >>>> rule out >>>> other parents for our HEDs. >>>> >>>> My new question, neophyte layman as I am, is: >>>> >>>> Does this new data/theory bring my initial question about >>>> Vesta-for-sure-as-parent-for-HEDs back into play? >>>> >>>> -Richard Montgomery >>>> >>> ______________________________________________ >>> Visit the Archives at >>> http://www.meteoritecentral.com/mailing-list-archives.html >>> Meteorite-list mailing list >>> Meteorite-list at meteoritecentral.com >>> http://six.pairlist.net/mailman/listinfo/meteorite-list >>> >> >> ______________________________________________ >> Visit the Archives at >> http://www.meteoritecentral.com/mailing-list-archives.html >> Meteorite-list mailing list >> Meteorite-list at meteoritecentral.com >> http://six.pairlist.net/mailman/listinfo/meteorite-list >> >> ______________________________________________ >> Visit the Archives at >> http://www.meteoritecentral.com/mailing-list-archives.html >> Meteorite-list mailing list >> Meteorite-list at meteoritecentral.com >> http://six.pairlist.net/mailman/listinfo/meteorite-list >> > > > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ > Visit the Archives at > http://www.meteoritecentral.com/mailing-list-archives.html > Meteorite-list mailing list > Meteorite-list at meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > Received on Sat 16 Apr 2011 10:43:28 PM PDT |
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