[meteorite-list] Discover magazine article

From: Sara Russell <sarr_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:12 2004
Message-ID: <E14XLwW-000709-00_at_pat.nhm.ac.uk>

Dear All,

Phil Bland, the subject of the Discover magazine article, is not on
Meteorite Central, but I forwarded the postings about it to him. His reply
is pasted below.

Sara Russell


>Its good to see that people still have so much faith in the printed word,
>however, we have here nothing more than a typo, which would have been
>apparent to anyone who had checked one of the several papers that I've
>written on this subject. So, to clarify:
>
>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. This estimate is from Bland et al. (1996), Monthly Notices of
>the Royal Astronomical Society 283, 551-565, which was our last major paper
>on the subject. We've also published an early version (in the same year) in
>Geochimica et Cosmochimica Acta 60, 2053, which may be more easily
>accessible. Its noteworthy that our estimate, and the mass distribution we
>define, our both consistent with estimates of Halliday et al. (1989)
>Meteoritics 24, 173, from the MORP camera network study, which was the best
>independent estimate of the flux of meteorites that we had to compare our
>work to. The main result was (a) we confirm the MORP result, and (b) there
>doesn't seem to be much change in flux over 50,000 years (which there
>shouldn't be, given what we know about asteroid delivery mechanisms, but its
>nice to show it).
>
>Finally, in response to Kelly Webb's somewhat hostile posting, and the
>suggestion that our method was largely worthless:
>We established both the ages over which the meteorites fell (my colleague
>Tim Jull has been doing this for a long while, and we used his existing
>ages, and also some new ones that he ran specifically for this study), and
>also (contrary to Webb's suggestion) the degree of weathering that the
>samples had experienced. That was the main significance of our methodology:
>putting age and degree of weathering together, you can get the weathering
>rate ie. the rate at which meteorites are being removed from a population.
>Knowing how many samples are on the ground today, in a given area, we can do
>a flux calculation for any meteorite accumulation. While its not perfect,
>the fact that we get essentially the same results (within error) for 3
>different hot desert populations, and they agree with the MORP data,
>suggests to me that there is some value in this approach.
>
Received on Mon 26 Feb 2001 06:35:52 AM PST