Dear Doug, Larry and List,
Thanks for the response from you both and from Sr
Gallo in Venezuela! Upon further reflection, I am not
sure how much information can be gained from
micrometeorite lunar dust grains...the problem is that
you have only one or two mineral grains...maybe three.
But what you lack in macroscopic petrological context,
you might gain in microscopic studies involving
isotopes, studies of polymorphic forms, and odd
minerals (e.g. Hapkeite) etc.
But then there is the whole problem of
identification of lunar micrometeorites, not an easy
one to solve, especially, as Larry says (and I agree)
they are likely to be rare.
Hmmmm. I like your suggestion that this would be an
interesting project to critically examine, in
conjunction with an educational project.
Francis Graham
--- mexicodoug <[EMAIL PROTECTED]> wrote:
Dear Francis,
I was thinking exactly the same angle already posted
by Larry, so let me
just comment on your question:
"And at what size level does a meteorite cease to be
of interest?"
by offering the opinion:
At the level it ceases to contain any information
attributable to
meteoroids, meteorites or their parent bodies.
Since this will change with
time and technology, the question may be time and
resource dependent.
However, your inquiry about whether any of these
particles have been
analyzed (or imo, capable of being analyzed at
present), stands.
It would seem to me, that a very good project for
schools would be to
organize a collection protocol for educators in the
style of the superb
International Monarch Butterfly tagging program (or
also like SETI on home
computers), to collect large amounts of this
material, set up a factorial
experimental design to test certain hypothesis and
bulk sample differences,
by appropriately submitting these for testing.
I would imagine that this is an experiment that
neither the ESA nor NASA
have the resources nor mandate to do, yet could lead
to profound insight on
the nature of cometary particles on Earth and make a
very good contribution
to science by enthusiastic young scientsits to be.
Or I darkly suspect,
more likely an application of the scientific method
to disprove a popularly
held theory theory regarding most of the materials
recovered in this way -
either way, a great exercise for teaching meteorites
and science in general
with a problem, methodology, and a participative
attitude.
Surely there is some work on this out there, but
sample size and scope
restrictions make this an ideal educator's project
looking only for someone
like you to organize. Just need a partner in the
scientific community
willing to lead in the intrumental analyses and
sample preparation.
Best Wishes and Good Health,
Doug
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: "Francis Graham" <[EMAIL PROTECTED]>
Cc: <[email protected]>
Sent: Tuesday, November 20, 2007 8:49 AM
Subject: Re: [meteorite-list] Brownlees in Rainwater
> Hello Francis:
>
> I do not pretend to be an expert on this subject,
but the simple answer to
> at least oneof your questions is that there is no
indication that any of
> the micrometeorites (and thus what you might get
in rainwater) is
> planetary or lunar. The ones collected in the
upper atmosphere are either
> from asteroids or comets. It may be that some very
small percentage is
> planetary/lunar, but these might be so rare as to
be lost in the noise.
>
> Larry Lebofsky
>
> On Tue, November 20, 2007 7:31 am, Francis Graham
wrote:
>> Dear List
>> I have a question which has been vexing me for
some
>> years. I was introduced to a method of collection
of
>> micrometeorites by Larry Megahan some years ago,
which consisted of
>> collecting rainwater and then wrapping a powerful
rare Earth magnet in
>> Saran (TM)wrap. Placing
>> the Saran wrap on a glass plate, and examining it
under the microscope,
>> one
>> could see many ferromagnetic particles. Some were
rounded and ablated and
>> it was a strong guess that these were
micrometeorites. I have had some
>> students try this project and indeed some of the
particles are
>> microspheroids of ablated iron, similar to so
called "Brownlee particles"
>> colected in the stratosphere. But I have reason
to be suspicious,
>> especially if the collection is near a former
industrial or mining site.
>> MY
>> QUESTION IS, has this method, widely circulated
>> in presecondary teaching circles, ever been
critically evaluated by
>> electron microprobe analysis, X-Ray fluorescence
or some such? And at
>> what
>> size level does a meteorite cease to be of
interest? It would naively
>> seem,
>> that although a very very very tiny percentage of
meteorites are lunars
>> or
>> Martians, if a way to rapidly identify
micrometeorites
>> can be done, a lot more information on Mars and
the Moon could be
>> obtained,
>> simply because there are so many micrometeorites.
This would include
>> collection in the stratosphere as Brownlee did,
maybe piggybacked on
>> surveillance aircraft. But one question at a
time.
>> Francis Graham
>>
>>
>>
>>
>>
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