[meteorite-list] NWA 5400: Earth-Related Meteorite

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Thu, 10 Jun 2010 09:31:41 -0400
Message-ID: <AANLkTikm1LdoIvmGOplJPM1CAtS4bVMHqEUjAihpL21h_at_mail.gmail.com>

Hi Sterling and List,

As usual Sterling - very lucid and well said. :)

I'm summarize for those who didn't read all of Sterling's reply -

"Let's not get carried away here...." LOL

Best regards,

MikeG


On 6/10/10, Sterling K. Webb <sterling_k_webb at sbcglobal.net> wrote:
> Hi, List,
>
> The theoretically possible origins of NWA are specific:
> http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2332.pdf
> "Alternative possibilities are that the new specimen
> is (a) a terrene meteorite, (b) a Theian meteorite, or
> (c) a meteorite related to another former differentiated
> body accreted near Earth... The very different Fe/Mn
> ratios in olivine and pyroxenes set NWA 5400 apart
> from any known lunar rock, as well as any modern
> terrestrial rock from Earth's crust or shallow mantle
> (especially given the presence of accessory FeNi metal).
> In texture, mineralogy and mineral compositions, NWA
> 5400 resembles some brachinites, but those ancient
> achondrites have very different oxygen isotope compositions...
> The giant collision of Theia with proto-Earth (or collisions
> involving other Earth-like bodies) may have resulted in
> the ejection of some asteroid-sized fragments of one or
> both colliding bodies into orbits that precluded their
> reaccretion to Earth or Moon. Some such spalled
> fragments could have been (1) accreted to or captured
> as satellites by other extant planets, (2) captured by
> the Sun, or (3) trapped within the main asteroid belt.
> In the last case, such bodies could be targets for very
> recent impacts and collisions, and delivery of material
> as meteorites to Earth."
>
> Specific in that it could only be a "terrene" meteorite
> if it came from the Earth BEFORE it collided with Theia
> (the Mars-sized future Moon). It's not a chip of Earth
> from the last 4.4 billion years.
>
> Or it could be a "Theian" meteorite from BEFORE Theia
> collided with the Pre-Moon Earth. That would make it
> OLDER than the collision.
>
> Or it could be from a third (or fourth or fifth...) body
> that accreted in the Earth-Theia orbit BEFORE the
> Pre-Moon Earth - Theia collision and was ejected from
> the Earth orbit by the new more-massive Earth.
>
> Or it could be from an asteroidal fragment OF that
> collision which was batted out into the Belt (I call this
> the "long fly ball" theory) from which this is a chip
> that got here the way most meteorites do.
>
> Or it could be from a large asteroid fragment of that
> collision that was captured by Venus as a retrograde
> moon which spiraled in and broke up but this piece
> is from a fragment that escaped re-entry to Venus and
> was cast onto an asteroidal orbit that supplies a meteorite
> rarely.
>
> It has NOT wandered around until now when it landed
> on the modern Earth.
>
> Or...
>
> Please, I'm getting dizzy.
>
> Can it be made simple? OK, every other non-lunar,
> non-planetary meteorite we know of has been shown to
> be or is presumed to come from a smallish body whose orbit
> takes it through or places it in the Asteroid Belt. The odds
> are pretty good that this one did too. It got here the way
> almost all meteorites do.
>
> Dump the thought that this one stone wandered around
> for 4.4 billion years and then hit the Earth. The odds against
> that simple story are colossally high. "Astronomical" is too
> small to describe the odds against that notion.
>
> On the other hand, we have 100,000 meteorites AND
> this one. There must be something unusual about its
> life story, worthy of an interview by Oprah or Ted Koppel.
>
> It could have come from a very small asteroid
> that does not often send a rock to Earth, or an asteroid
> that is placed in an unusual orbit with characteristics
> that make Earth-delivery difficult and hence rare.
>
> Another thing to bear in mind. Our sample of
> 100,000 meteorites is NOT a sample of 4.5 billion
> years of time. It is a sample of the meteorites that
> have made it to Earth in the last 100,000 years
> or less (except for a small handful of Antarctic ones
> that might be 370,000 years on Earth or more).
>
> Yes, we have "fossil meteorites" and traces that are
> too terrestrialized to tell us much except that meteorites
> (and asteroids) have always fallen to Earth and always will.
> But our present collection is a thin slice of time, of the
> present parent-body supply, a supply which almost
> certainly changes over long periods of time.
>
> Thousands of NWA 5400-type meteorites could have
> fallen to Earth over millions (and billions) of years and
> we would never know it unless one fell in the last fifty
> or a hundred thousand years.
>
> ONE did.
>
> The problem is identified nicely by the authors of the
> second LPI paper Greg mentioned -- they called it the
> "storage" problem. Where have you been hiding, little
> felllah, for all this time?
>
> My money's on the Asteroid Belt.
>
>
> Sterling K. Webb
> --------------------------------------------------------------------------
> ----- Original Message -----
> From: "Richard Kowalski" <damoclid at yahoo.com>
> To: "Greg Hupe" <gmhupe at htn.net>; <meteorite-list at meteoritecentral.com>;
> "Stuart McDaniel - Action Shooting Supply"
> <actionshooting at carolina.rr.com>
> Sent: Wednesday, June 09, 2010 10:34 PM
> Subject: Re: [meteorite-list] NWA 5400: Earth-Related Meteorite
>
>
>>I don't want to speak for Greg, but yes, that is one possible origin.
>> It could be from the proto-Earth, the Mars sized impactor that stuck
>> the proto-Earth, (this is the impact that formed the moon) or the
>> remnants of that event.
>>
>> No matter which, it is an awesomely exciting meteorite!
>>
>> --
>> Richard Kowalski
>> Full Moon Photography
>> IMCA #1081
>>
>>
>> --- On Wed, 6/9/10, Stuart McDaniel - Action Shooting Supply
>> <actionshooting at carolina.rr.com> wrote:
>>
>>> From: Stuart McDaniel - Action Shooting Supply
>>> <actionshooting at carolina.rr.com>
>>> Subject: Re: [meteorite-list] NWA 5400: Earth-Related Meteorite
>>> To: "Greg Hupe" <gmhupe at htn.net>, meteorite-list at meteoritecentral.com
>>> Date: Wednesday, June 9, 2010, 5:30 PM
>>> So this could be a piece of Earth
>>> before Earth was Earth??
>>>
>>>
>>> Stuart McDaniel
>>> Lawndale, NC
>>> Secr., CCAS
>>> ----- Original Message ----- From: "Greg Hupe" <gmhupe at htn.net>
>>> To: <meteorite-list at meteoritecentral.com>
>>> Sent: Tuesday, June 08, 2010 7:31 PM
>>> Subject: [meteorite-list] NWA 5400: Earth-Related
>>> Meteorite
>>>
>>>
>>> > Dear List Members,
>>> >
>>> > I would like to announce an important new meteorite
>>> that has been under intense analysis over the last two years
>>> by a select group of scientists from around the world...
>>> >
>>> > NWA 5400: Earth-Related Ungrouped Meteorite
>>> >
>>> >
>>> > Northwest Africa 5400 may be a sample from a large
>>> asteroid or dwarf planet, which accreted in the early solar
>>> nebula in the vicinity of proto-Earth or Theia. NWA 5400 has
>>> oxygen isotope ratios indistinguishable from those of rocks
>>> from the Earth and the Moon, which plot on the TFL
>>> (Terrestrial Fractionation Line). A precise formation age
>>> has not yet been measured, but it cannot be older than 4.54
>>> billion years, which likely makes NWA 5400 anomalously young
>>> among primitive achondritic objects from the early Solar
>>> System. It is generally accepted that the Earth-Moon system
>>> was created when Theia collided with proto-Earth about 4.3
>>> billion years ago. Is it possible that NWA 5400 is somehow
>>> related to this phenomenal event?
>>> >
>>> >
>>> >
>>> > NWA 5400 adds valuable understanding of events that
>>> took place in the early evolution period of the Solar
>>> System. After two years of intense analysis, scientists at
>>> prominent institutions from around the world continue to
>>> diligently study this 'stand-alone' meteorite, which will
>>> add to the already incredible information NWA 5400 has to
>>> offer.
>>> >
>>> >
>>> >
>>> > Link to 2009 LPSC abstract on NWA 5400:
>>> >
>>> > http://www.lpi.usra.edu/meetings/lpsc2009/pdf/2332.pdf
>>> >
>>> >
>>> >
>>> > Link to 2010 LPSC abstract on NWA 5400:
>>> >
>>> > http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1492.pdf
>>> >
>>> >
>>> >
>>> > NWA 5400 has a Total Known Weight of 4.818 kg in a
>>> single stone that was discovered in Northwest Africa in
>>> 2008. The chocolate-brown mottled matrix takes an extremely
>>> nice polish, which reveals the dazzling olivine crystals
>>> exhibited in this scientifically important new meteorite!
>>> >
>>> >
>>> >
>>> > Cross-polarized light optical thin section image of
>>> NWA 5400 (width of field = 1.2mm):
>>> >
>>> > http://www.lunarrock.com/NWA5400/nwa5400xpl.jpg
>>> >
>>> >
>>> >
>>> > Image of 58.9-gram complete slice with hologram-like
>>> olivine crystals that dance across the polished surface when
>>> tilted from side to side:
>>> >
>>> > http://www.lunarrock.com/NWA5400/nwa5400slice.jpg
>>> >
>>> >
>>> > Best regards,
>>> > Greg
>>> >
>>> > ====================
>>> > Greg Hupe
>>> > The Hupe Collection
>>> > NaturesVault (eBay)
>>> > gmhupe at htn.net
>>> > www.LunarRock.com
>>> > IMCA 3163
>>> > ====================
>>> > Click here for my current eBay auctions:
>>> > http://search.ebay.com/_W0QQsassZnaturesvault
>>> >
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>>> >
>>>
>>>
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>>
>>
>>
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-- 
------------------------------------------------------------
Mike Gilmer - Galactic Stone & Ironworks Meteorites
http://www.galactic-stone.com
http://www.facebook.com/galacticstone
------------------------------------------------------------

Received on Thu 10 Jun 2010 09:31:41 AM PDT