[meteorite-list] Phil Bland article

From: Sara Russell <sarr_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:12 2004
Message-ID: <E14Xkws-0004n7-00_at_pat.nhm.ac.uk>

Dear Rob and everyone,
Here is Phil's reply-
Sara


>>> >The actual sentence should have read 'roughly 100 meteorites
>weighing
>>> more
>>> >than 10 grams per million square miles per year' ie. not 40 million
>>> square
>>> >kilometers.
>>>
>>Actually, if I'm not mistaken, the Discover article said
>>40 million square miles, not kilometers.
>
Sorry, yep, my mistake, I didn't see that they'd used miles - I have trouble
spotting US units I'm afraid. Our data is all given in kilometers, so: 100
10 grams per 10^6 square kilometers per year is the (absolutely final!)
estimate. I think that should make some distance to the shortfall that we
see in our estimate.

>>
>>> >Knowing how many samples are on the ground today, in a given area,
>we can
>>> do
>>> >a flux calculation for any meteorite accumulation.
>>>
>>This is your greatest potential source of error. You don't
>>know how many samples are on the ground today--you only know
>>how many have been found.
>
We (or others) paired everything that was found to try and get back to
original number of meteorites, instead of fragments. Estimates for numbers
of meteorites per unit area in Roosevelt County come from Mike Zolensky's
work. This comparatively small area has been effectively soured for
meteorites on several trips, and the collection is well paired, so I think
that's solid. In the Nullarbor we took the most well searched areas for our
estimate of number per unit area, such as the Camel Donga strewn field which
has been visited many times. The Sahara estimate was less well constrained,
but a look at the mass distribution for meteorites recovered there shows
that over about 150 grams you get the expected slope. Following discussions
with some collectors we were able to (in some cases) work out the area they
searched, and thus get the number per unit area in the Sahara for meteorites
150 grams - as we know the mass distribution well down to smaller objects,
from our work, Zolensky's work, and Halliday's work, it seems reasonable to
extend this down to 10 grams.
Received on Tue 27 Feb 2001 09:17:54 AM PST