[meteorite-list] Info on Sikhote Alin's shrapnel

From: Jason Utas <meteoritekid_at_meteoritecentral.com>
Date: Tue, 17 Nov 2009 04:48:11 -0800
Message-ID: <93aaac890911170448x25f1ebbcka2ed031308b0b1e8_at_mail.gmail.com>

Hello Graham, All,

On the contrary, the typical pieces of "shrapnel" found were in my
opinion formed exclusively on impact - the force of the explosive
impacts was certainly adequate to drive sizable fragments through
practically any tree (well, let's exclude things like Sequoias...).

There are two types of Sikhote-Alin fragments, though. There are the
pieces that show atmospheric fragmentation - these typically exhibit
surfaces that appear torn but are not technically "shrapnel."
Then there are the specimens that formed upon impact - the torn,
jagged "shrapnel" pieces.

Here are examples of each:


Atmospheric Tear:


www.aerolite.org/.../ sikhote-alin-aaa-33-2.htm

http://upload.wikimedia.org/wikipedia/commons/archive/a/ab/20050827232208!SikhoteAlinMeteorite.jpg

http://sk.wikipedia.org/wiki/S?bor:SikhoteAlinMeteorite.jpg


Then you have the impact fragments:


http://www.carionmineraux.com/mineraux/mineraux_decembre_2008/meteorite_sikhote_alin_top_1.jpg

http://lh6.ggpht.com/_4j-MWz4xHuI/SU-HOSQNOgI/AAAAAAAAAII/CwiJw7cjXTw/Sikhote_Alin_78gram_01.jpg


Right - I just got Jeff's message...mhm.
Regards,
Jason




On Tue, Nov 17, 2009 at 4:09 AM, <ensoramanda at ntlworld.com> wrote:
> Hi Fred, List,
>
> How does that explain all the shrapnel found in the sides of the trees or holes straight through standing trees? Surely shrapnel was produced both on the way down and on impact?
>
> I have pieces that seem to have no sign of ablation, just lots of shear lines.
>
> Graham, Uk
>
> ---- debfred at att.net wrote:
>> ? List, I have searched many Kilos of SA shrapnel without ever finding ONE without some surface melting. From what I have seen shrapnel is ALL air shredding with subsequent atmospheric frictional melting.
>> Cheers, Fred Olsen
>> -------------- Original message ----------------------
>> From: <ensoramanda at ntlworld.com>
>> >
>> I did not know heat was needed at all to form shrapnel...surely it is just due
>> to shearing of fragments from the dramatic collisions of fragments on impact or
>> during exposive events on the way down that did not leave enough time for
>> > ablation?
>> >
>> > Graham UK
>> >
>> > ---- Maurizio Eltri <maurizio.eltri at libero.it> wrote:
>> > > Hi all,
>> > >
>> > > I ask to those who are more experienced
>> > > than me,clarification about Sikhote Alin's
>> > > splinters formation.
>> > > In my opinion there can be two ways to
>> > > justify the origin of the fragments found in
>> > > the vicinity of the largest craters,
>> > > 1) The kinetic energy released at the contact
>> > > surfaces of meteorite/ground was enough to
>> > > melt the frontlayer of the meteorite with
>> > > the subsequent violent expulsion of fragments,
>> > > fused or partially fused.
>> > > 2) Having the meteorites reached the retardation
>> > > point at only 5 km of altitude, they would arrived
>> > > at an impact with their hot surfaces, this would
>> > > facilitate the expulsion of splinters.
>> > > I apologize for my bad English.
>> > > Maurizio Eltri
>> > >
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>>
>>
>>
>
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Received on Tue 17 Nov 2009 07:48:11 AM PST