[meteorite-list] MPOD Feb. 20th 2014

From: Graham Ensor <graham.ensor_at_meteoritecentral.com>
Date: Fri, 21 Feb 2014 23:18:32 +0000
Message-ID: <CAJkn+kaVE+PnTY65G_-imq_iNwBJjMP0mi5cmQmye6jk5q+ooQ_at_mail.gmail.com>

Hi Rob...I think the answer is that because it was such a large event
all those scenarios happened at some point along the path, before
during and after it detonated....Much like Sikhote alin...apart from
the cratering impacts...similarly Sikhote Alin still to this day
surprises us with new variations, but for an iron meteorite. I imagine
Chelyabinsk still has some surprise variations to come.

Graham

On Fri, Feb 21, 2014 at 9:47 PM, Rob Lenssen <rlenssen at planet.nl> wrote:
> Hi List,
>
> Thank you for your on and off List replies. Main focus in the answers was
> the extreme violence of the Chelyabinsk explosion.
> Yes, this bolide, and the amount of energy released, was much larger than
> average. I'm still wondering what mechanism could produce such a crust
> though.
>
> This kind of extreme (all-around) foamy crust is uncommon in typical
> chondrite falls, but I have seen quite some examples in the case of
> Chelyabinsk already.
> It might have something to do with the size of this bolide. But again, what
> was the mechanism?
>
> Like Gregor states in his MPOD contribution (here's the link again for your
> convenience: http://www.tucsonmeteorites.com/mpodmain.asp?DD=2/20/2014&WYD=
> ), one would expect the stone to have been in a low pressure environment
> when the crust solidified. Foaming typically requires an under-pressure,
> like in the case of the back side of an oriented specimen.
> This specimen however has foamy crust (almost) all around. Could it have
> anything to do with the constituents of the fragment? Or did the sheer
> magnitude of the Chelyabinsk "explosion" produce a vacuum uncommon to
> smaller Falls? Could it like Gregor proposed have been flying in the low
> pressure zone behind a larger piece?
> Still wondering...
>
> Best regards,
> Rob Lenssen
>
>
>
> -----Oorspronkelijk bericht-----
> Van: meteorite-list-bounces at meteoritecentral.com
> [mailto:meteorite-list-bounces at meteoritecentral.com] Namens Ron Baalke
> Verzonden: donderdag 20 februari 2014 21:33
> Aan: Meteorite Mailing List
> Onderwerp: Re: [meteorite-list] MPOD Feb. 20th 2014
>
>>
>> A great little Chelyabinsk, with thick foamy crust as MPOD today:
>> http://www.tucsonmeteorites.com/mpodmain.asp?DD=2/20/2014&WYD=
>> Thanks for showing Paul!
>>
>> Contributor Gregor asks: "Does anyone have an explanation for that
>> kind of fusion crust?"
>> I too would be interested in an answer. Anybody?
>>
>
> The piece of Chelyabinsk I have shows two types of melting. I think one is
> due to the normal ablation going through the atmosphere, and the other from
> when the fireball exploded.
>
> ron
>
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Received on Fri 21 Feb 2014 06:18:32 PM PST