[meteorite-list] Cold Asteroids May Have A SoftHeart(AllendeMeteorite)

From: lebofsky at lpl.arizona.edu <lebofsky_at_meteoritecentral.com>
Date: Sat, 16 Apr 2011 09:27:46 -0700
Message-ID: <2aed3a20b7679731b8a25fb1420fb22b.squirrel_at_webmail.lpl.arizona.edu>

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
>
Received on Sat 16 Apr 2011 12:27:46 PM PDT