[meteorite-list] Brownlees in Rainwater

From: Francis Graham <francisgraham_at_meteoritecentral.com>
Date: Tue, 20 Nov 2007 09:42:37 -0800 (PST)
Message-ID: <542152.56440.qm_at_web58703.mail.re1.yahoo.com>

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 <mexicodoug at aol.com> 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: <lebofsky at lpl.arizona.edu>
> To: "Francis Graham" <francisgraham at rocketmail.com>
> Cc: <meteorite-list at meteoritecentral.com>
> 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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Received on Tue 20 Nov 2007 12:42:37 PM PST