[meteorite-list] Norway meteorite impact site found (NOT)

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Wed Jun 14 10:17:15 2006
Message-ID: <A8044CCD89B24B458AE36254DCA2BD07A4EB2C_at_0005-its-exmp01.us.saic.com>

Hi All,

I'm with Marco, Chris and others on this one: that's not an impact
site. If people are looking for something this large, they'll never
find it. I highly doubt the Norwegian bolide was even as large as a
soccer ball (er, football), in which case it would have hit the ground
at terminal velocity -- far too slow to cause anything more than a
dent in the ground. On hard rock it simply would have bounced, and
possibly broken into smaller pieces.

Finding the meteorite or meteorites is going to take a great deal
of effort -- remember how long it took to find the Neuschwanstein
meteorites? They had the benefit of a very accurate 3-D track and
impact point prediction based on multiple all-sky cameras, but
because of the nature of the terrain where it landed it still
took months to find the first piece. Here, we don't have the
benefit of an accurate track, so the potential impact area covers
thousands of square kilometers. I would say it was completely
hopeless were it not for the existence of the one photograph and
the seismic/sonic recordings.

--Rob

-----Original Message-----
From: meteorite-list-bounces_at_meteoritecentral.com
[mailto:meteorite-list-bounces_at_meteoritecentral.com] On Behalf Of Chris
Peterson
Sent: Tuesday, June 13, 2006 6:38 AM
To: Meteorite List
Subject: Re: [meteorite-list] Norway Meteorite Impact Site Believed to
be Found


Hi Sterling-

You are quite mistaken in this regard. Seismic events are routine with
moderate and large fireballs. I've optically recorded five in the last
few
years that produced signals on seismometers in northern New Mexico
(there
may well be others for which I didn't check). The fireball over the
Pacific
Northwest a couple of years ago was actually tracked by its effect on an

array of seismometers. Even sonic booms from airplanes are recorded on
seismometers. The effect of a large mass of air on the ground is
significant.

On the other hand, I'm not aware of any actual impacts producing
measurable
seismic signals. It would require extraordinary circumstances for a 1m
iron
to reach the ground at anything other than ordinary terminal velocity,
and
an ordinary fall will not generate a significant seismic signal unless
it
nearly hits the seismometer! And it doesn't make much difference whether

it's iron or stone.

There is nothing about the recorded seismic signal in Norway that makes
me
think this was anything other than an ordinary (large) fireball, or that

anything reached the ground with hypersonic velocity.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
Received on Tue 13 Jun 2006 02:51:55 PM PDT