[meteorite-list] MPOD Feb. 20th 2014

From: Rob Lenssen <rlenssen_at_meteoritecentral.com>
Date: Fri, 21 Feb 2014 22:47:22 +0100
Message-ID: <001501cf2f4e$80833230$81899690$_at_planet.nl>

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 04:47:22 PM PST