[meteorite-list] Two clarifications on prior post

From: Matson, Robert <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Thu Apr 22 09:55:41 2004
Message-ID: <AF564D2B9D91D411B9FE00508BF1C8698E589D_at_US-Torrance.mail.saic.com>

Hi again,

Dave Freeman was kind enough to e-mail me about a point
of confusion in my prior post. I didn't pay close enough
attention to Robert Beauford's last question:

> An object over 1 kilo (2.2 lbs) might fall in a given 1 square
> mile piece of land only once in every (how many) years?

I mistakenly answered the related question "An object over 1 kilo
might fall on a ? square mile piece of land once per year"
(following the example of the prior question). I based my
answer on a WAG (wild ass guess) at the ratio of falls producing
10-gram meteorites to falls producing 1-kilogram meteorites
(20 to 1). So, given my earlier answer that one 10-gram
meteorite per year falls on a 5000-square-mile plot of land,
this is equivalent to saying on average that one 10-gram
meteorite falls every 5000 years on a 1-square-mile plot of
land. Assuming that 20:1 ratio kilo-to-10-gram ratio was
correct, that would mean you'd need to wait 100,000 years
on average for a 1 kilo meteorite to land in a given 1 square
mile area.

However, these numbers are all based on *falls* per unit time,
not meteorites per unit time. Since each fall usually produces
a number of meteorites (sometimes thousands or even tens of
thousands!), this changes the statistics on numbers of non-
unique 10-gram or 1-kilo meteorites per given area. To really
solve the problem, you'd need to know more about the statistics
of strewnfield areas, and average numbers of 10+ gram and 1+ kilo
meteorites dropped per fall.

Best,
Rob
Received on Sun 06 Jan 2002 09:40:23 PM PST