Op 24-11-2010 16:55, Murray Paulson schreef:
Hi Marco:
The short lived isotopes decayed 4.5 - 4.6 or so billion years ago,
and only warmed the acreeted asteroid at that time. They are but a
distant memory when the meteorite falls here on earth today.
Hi Murray
No, you are mistaken. It is not a fossil process happening during solar system
formation only. Shortlived isotopes form continuously in a meteorite up to the
present day under the influence of cosmic radiation. They are being formed up to
the moment the meteoroid plunges into our atmosphere.
Only when the meteorite is at the earth surface and shielded from cosmic
radiation, does the production of these shortlived isotopes stop. They decay in
the minutes, hours, days and weeks after the fall, depending on their half lives.
This is the reason why a fresh meteorite fall needs to be measured for them as
soon after a fall as possible. Only during a short timne after the fall, this
can be done.
- Marco
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Dr Marco (asteroid 183294) Langbroek
Dutch Meteor Society (DMS)
e-mail: d...@marcolangbroek.nl
http://www.dmsweb.org
http://www.marcolangbroek.nl
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