[meteorite-list] Publications of the Carancas event ADDITIONAL

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Tue, 9 Oct 2007 21:02:30 -0500
Message-ID: <14fc01c80ae1$9e597000$b92ee146_at_ATARIENGINE>

Hi,

    Yes, the fact that the dissociation of the troilite would
explain the strange odors and reported "illnesses" convinces
me that it got at least that hot. Troilite's vapor point is 700 K.
or 427 C. and it would dissociate immediately in the presence
of water or even just humidity.

    That even sets a lower limit to the heat produced by the
impact. It could always have generated more heat than that.
At impact, the kinetic energy of the stone goes from being
"potential" energy to being thermal energy. The entire object's
temperature is "instantly" increased.

    The troilite goes from a cold solid to a hot vapor and in
so doing expands many times in volume... or tries to. I
haven't worked out the actual ratio of increase because you
don't have to. ALL solid to gas transitions increase volume
and/or pressure by a huge factor; that's how explosives work.

    So, no big rock in the mudpit, but maybe lots of fragments.
Recovering them would tell you a lot. The stuff found outside
the crater was blasted off the backside of the object by the shock
of the impact and wasn't subjected to the full heating. But stuff
from inside the crater would reveal whether there was any rock
melt, or even rock vaporization.

    Thermal alteration would establish how hot it got and that
would let you calculate the impact speed very reasonably. A
total absence of fragments is unlikely. There would be some
of the free iron from the meteorite at a minimum, even if the
rock was pulverized.

    Water appears to be moving through the crater, though;
it's in a riverbed. Material is being washed away constantly.
It may be too late, or perhaps only heavy items will remain.
And the rainy season is coming, as Mike tried to point out
to the local authorities. You can only do what you can do.
It's been almost a month. I wonder how long it will take the
Peruvians to "mobilize"?


Sterling K. Webb
-----------------------------------------------------------------
----- Original Message -----
From: "Charlie Devine" <moonrock25 at webtv.net>
To: "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
Cc: <meteorite-list at meteoritecentral.com>
Sent: Tuesday, October 09, 2007 8:02 PM
Subject: Re: [meteorite-list] Publications of the Carancas event ADDITIONAL


You wrote:

>It may have been only the less energetic
>vaporization of the 5% to 8% of the
>meteorite that was troilite that was the
>"bright flash" rather then the vaporization
>of the entire stone. Still, that alone would
>have been enough to shatter the impactor
>into fragments (or dust).

If that were the scenario, would an observation posted to the list on
10/5 by Piper R. W. Hollier
seem a reasonable expectation: "Troilite dissociates at high
temperatures (e.g. hypersonic impact), releasing hot sulphur vapor,
which in turn will oxidize in air to form sulphur dioxide, a very
irritating poison".
At the time Piper's theory as to why all the sickness was reported
seemed to me to be the best explanation for the reports. Would the
above scenario support that notion?

Charlie D.
Received on Tue 09 Oct 2007 10:02:30 PM PDT