[meteorite-list] PF fall duration

From: Marco Langbroek <marco.langbroek_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:34 2004
Message-ID: <003801c32c52$66fb9510$e8204451_at_HAL>

Steve wrote:

> Does anyone have the actual rate of fall already calculated? Is the fall
> time a universal law of physics learned by all meteoritic students in
> "Strewnfields 101" class?


I have some indicative data for you from the Dutch Glanerbrug fall. This hit
a house and shattered, and Peter Jenniskens was able to determine from the
fragment size distribution that the velocity upon impact was of order 30-120
meter/s (see P. Jenniskens et al., Pub. Astr. Inst. Czech. no. 79 (1992),
1-18).
If we take that as a typical value, it would take some 2.5 minutes to come
down from 15 km altitude.

Casper ter Kuile made a model calculation of the free fall of Glanerbrug
which does take in account atmospheric drag on the falling meteorite. For an
object (assumed spherical) of about 1 kg falling in free fall from 25 km
altitude, this indeed
provides impact velocities of order 50-110 meter/s, and a fall duration of
some 3 minutes. (see Radiant (J. Dutch Meteor Soc.) 12 (1990), 78-80).

So yes: the actual impact of a meteorite will occur a few minutes after the
fireball in a typical case.

- Marco

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Marco Langbroek

marco.langbroek_at_wanadoo.nl
meteorites_at_dmsweb.org
http://home.wanadoo.nl/marco.langbroek

"What seest thou else
 In the dark backward and abysm of time?"

                            William Shakespeare
                            The Tempest act I scene 2
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Received on Fri 06 Jun 2003 01:38:08 PM PDT