[meteorite-list] Marsden Canadian fall

From: Rob Matson <mojave_meteorites_at_meteoritecentral.com>
Date: Sun, 30 Nov 2008 16:59:09 -0800
Message-ID: <GOEDJOCBMMEHLEFDHGMMEECODKAA.mojave_meteorites_at_cox.net>

Hi All,

One aspect of this new Canadian fall amuses me in particular. In
the original report, we had quite a few "facts" about the bolide:

> SASKATOON - A fireball that lit up the skies of Alberta and
> Saskatchewan last Thursday evening was a chunk of low-flying
> asteroid that weighed about 10 tonnes before it struck Earth's
> atmosphere, according to a University of Calgary investigation.

> University of Calgary researcher Alan Hildebrand has outlined a
> region in western Saskatchewan where he expects to find desk-sized
> fragments of the space rock.

Of course, these first two paragraphs are quite inconsistent with
each other -- a bolide that weighed only 10 tonnes *before* it hit
the atmosphere would be the size of a SINGLE desk. That's prior to
atmospheric ablation, which certainly would have reduced the mass
by 70-90%. How do you find "desk-sized fragments" on the ground
following ablation of a single desk-sized original object?

> The fireball pierced the atmosphere at a steep angle of about
> 60 degrees off the horizontal and lasted about five seconds.

The steep entry angle suggests catastrophic break-up into many
pieces -- most of them small compared to the size of the original
meteoroid. Obviously not desk-sized or even television-sized. Mind
you, it's still an impressive fall. But I don't understand the
need for hyperbole.

How quickly people forget that we had an asteroid of KNOWN size
(to within a factor of two) and orbit that entered over Sudan at
a lower initial velocity and a much shallower angle, and yet
"officials" poo-pooed that anything significant would reach the
ground. This asteroid was at least 40 tons and quite possibly
over 100 tons, had an orbit that intersected that of Mars
(suggesting a possible SNC), and impacted in a location that
would have been child's play to recover -- if it weren't for
the minor matter of its landing in a third-world, genocidal
disaster area of a country.

I guess the point I'm trying to make is that the Sudan fall went
off the radar almost immediately, yet was a far more substantial
and scientifically important fall. But it seems not even meteorites
are immune from sectionalism. -Rob
Received on Sun 30 Nov 2008 07:59:09 PM PST