[meteorite-list] Orionoid micrometeorites

From: Jeff Grossman <jngrossman_at_meteoritecentral.com>
Date: Tue, 23 Oct 2012 09:30:16 -0400
Message-ID: <00a501cdb122$8c189c80$a449d580$_at_gmail.com>

In confirmation of what Chris responded, this comes from Mike Zolensky, who
studies cosmic dust and curates the NASA collection. -jeff

Hi Brandon
I can take a stab at answering your questions. Many persons have tried this
experiment in the past, and invariably they have found that the collected
material is from windblown terrestrial dust, airborne waste from coal fired
power plants, airplanes, even debris from reentering spacecraft materials.
Even among collected magnetic grains the percentage of extraterrestrial
materials is less than 1 in a million. The Orionids originate from Comet
Halley, and enter the atmosphere at very high velocity (~80 km/s), pretty
much guaranteeing that all the comet dust gets oxidized, melted, and
vaporized. The magnetic materials you have probably contains magnetite,
which is also attracted to magnet, and probably mainly derives from power
plants.
Sorry to discourage you. 25 years ago Bill Cassidy and Bob Wittkowski tried
your experiment at the South Pole, where it is much cleaner than anywhere in
the US. They came up with essentially no micrometeorites. Last year we
repeated this experiment on a remote pacific Atoll, and even there we expect
to have to wade through millions of terrestrial grains to find a few
micrometeorites.
Mike
 
Michael Zolensky
KT NASA Johnson Space Center
Houston, TX 77058

> -----Original Message-----
> From: meteorite-list-bounces at meteoritecentral.com [mailto:meteorite-list-
> bounces at meteoritecentral.com] On Behalf Of Chris Peterson
> Sent: Monday, October 22, 2012 11:52 AM
> To: meteorite-list at meteoritecentral.com
> Subject: Re: [meteorite-list] Orionoid micrometeorites
>
> I doubt you were seeing micrometeorites, and almost certainly not Orionid
> micrometeorites. While there is iron in Halley's dust trail, it remains a
trace
> constituent. Orionid micrometeorites should be silicates, not iron
particles.
>
> You don't state the size of particles observed, but typical
micrometeorites
> are in the 1-10 um diameter range. These particles require months or even
> years to settle to the ground. Even huge
> micrometeorites- 100 um diameter- would require about 100 hours to reach
> the ground, so you wouldn't see them until days after the shower peak.
>
> I've recovered particles very much like what you describe (using a custom
> built micrometeorite collection device), and have subjected the most
> interesting to examination under an electron microscope (with dispersion
> analysis). All proved to be nothing more than industrial smokestack
debris-
> and I'm high in the Rockies where the air has a very low particulate
count.
> Where you live, I doubt you'd ever pick out micrometeorites from the vast
> array of industrial pollutants.
>
> Chris
>
> *******************************
> Chris L Peterson
> Cloudbait Observatory
> http://www.cloudbait.com
>
> On 10/22/2012 9:07 AM, b1dunovant at aol.com wrote:
> > Hello Listees. I hope everyone enjoyed the weekend.
> >
> > I live in the Chicago suburbs and was not able to view the Orionoid
> > meteor shower due to overcast skys and horrible light polution from the
> > city. Knowing this would be the case, Two weeks ago while cleaning the
> > gutters on the house I rinsed the entire roof off several times so that
> > the amount of shingle material left in the gutter was less and less each
> > rinse, until finally there was hardly anything coming off. Yesterday I
> > affixed a fine screen to the end of my drain shoots and collected all
> > the material that I was rinsing off. I soaked all the material in
> > anhydrous alcohol for several hours and dried then dried in silica gel.
> > What I had was a mix of different shigle materials, tiny twigs and
> > hopefully something of interest.
> >
> > I use a rare earth magnet to seperate the material into a pile of
> > magnetic and a pile of non-magnetic materials. The magnetic material was
> > them put in a petri dish and was sorted throught under high
> > magnification for hours removing small magnetic materials in the rough
> > shingle grit. After working all day doing this seperation i was left
> > with stuff that left me with my jaw dropped.
> >
> > What i was looking at were aerodynamiclly shaped black metalic pieces,
> > some perfectly round, some pancake shaped, some bars, a couple buttons
> > with rollover all around such as you would see in some indochinites, and
> > even severl tear-dropped pieces with unbroke tails. Under even higher
> > magnification you could see surface details and even multple skins on
> > some of the tear drops and bb's. Along with them there were also bb's
> > that looked slightly oxidized and were an orange color I assume were
> > missed during the initial roof rinses, however the the mass majority
> > were shiny black and had very fine sufrface detail under magnification.
> >
> > Is there a chance these are condensents of vaporized material from the
> > Orionoid shower? If not why such the high concentrations of unoxidized
> > aeroforms so dilicate I doubt would still have such perfect tails after
> > my rigourous rinsing ahead of the meteor shower.
> >
> >
> > Email me off list if your interested in pictures of what I've described
> > above. I would love to hear some feedback from the community! I should
> > have some pictures up for the masses to view shortly.
> >
> > Regards,
> >
> > Brandon D.
> > IMCA# 9312
>
> ______________________________________________
>
> Visit the Archives at http://www.meteoritecentral.com/mailing-list-
> archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
Received on Tue 23 Oct 2012 09:30:16 AM PDT