[meteorite-list] NJO - Votes

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Fri, 5 Jan 2007 19:10:41 -0600
Message-ID: <008701c7312f$7cc97570$b421e146_at_ATARIENGINE>

Hi,

    About an hour after Ron posted the first news story
about the NJO, with a link to the newspaper with a photo
that had a scale in it, I posted this:

    "Thankfully, they provide a scale, so a rough estimate
of volume can be made. The weight is given as 13 ounces,
or about 370 grams. Roughing up the volume on a cylinder
of the diameter and length of the object shown, I get a
density between 7 gm/cm^3 and 8 gm/cm^3, so it's
likely iron."

    Specifically, a rectangular prism 25mm x 25mm x 70mm,
or a cylinder 30mm by 80mm, covers that density range.
Of course, it's a potato, but I approximate its volume at 45
+/- 3 cc. That would be consistent with iron at that weight.

    Brass or copper would be 15-20% heavier and lead or silver
would be 50% heavier for that size. Iridium or osmium would be
200% heavier, and a plutonium reactor slug would be 130%
heavier. A meteorwrong of solid gold would be 150% heavier.
A slug of tin would be almost the same weight as iron, but
pure tin is not that common.

    The only other choice is copper or brass and for that,
the object would have to be no more than 39 +/- 3 cc in
volume. Its length is evident, but it would have to have
an average circularized cross section just under one inch
in diameter, to be the right volume to be copper or brass.
It looks bulkier than that to me, but it's hard to judge a
potato from photos, videos, TV.

    The density of iron meteorites is variable over a +/- 10%
range depending the other constituents; nickel has a density
of 8.9, while troilite lowers the bulk density of the iron. The
density of copper alloys and brass varies considerably
according to composition.

    Two days of rising publicity, but would it take you more
than two hours to measure its density, window a corner, do the
nickel test, give it a close squint, and so forth?


Sterling K. Webb
--------------------------------------------------------------
----- Original Message -----
From: "Matson, Robert" <ROBERT.D.MATSON at saic.com>
To: <mccartney at blackbearddata.com>; "Meteorite Mailing List"
<meteorite-list at meteoritecentral.com>
Sent: Friday, January 05, 2007 3:06 PM
Subject: Re: [meteorite-list] NJO - Votes


> Hi All,
>
> I was surprised that our local NBC affiliate in Los Angeles closed the
> news last night (just before Jay Leno) with a 30-second blurb on the
> mystery metal object from New Jersey. So I was finally able to see
> high-definition video of the object being rotated, allowing a better
> feel for the surface texture. It is a bit peanut-shaped, and certainly
> larger than a golf ball which means its specific gravity is
> correspondingly
> lower -- less than 7 I should think. The surface looked melted in some
> spots (like viscous drips), but in other areas I thought I could see
> glints from small, metallic crystal faces -- although not unlike the
> octahedrite crystals one sees in the higher quality Nantan pieces.
>
> If this had been a find rather than a fall, I'd be very encouraged
> by its density and appearance. But as a fresh fall, it looks, well,
> ~wrong~. Where is the crust of magnetite? How could it look the way
> it does if it just screamed through our upper atmosphere at 8+ miles
> per second?
>
> So my vote is that if it turns out to be a meteorite, foul play is
> involved. Determining whether it is a meteorite or not should take
> about 20 seconds by any regular member of this list examining the
> specimen firsthand. If it ~is~ a meteorite, the next step would
> be to check its gamma ray spectrum for evidence of short-lived,
> cosmic-ray-induced radioactive isotopes in order to prove it was
> recently in space.
>
> On a final note, by nature I'm suspicious of coincidences; given
> the recent reentry of the Soyuz third stage booster over Wyoming/
> Colorado the morning of January 4th, I thought it would be a good
> idea to check that rocket body's ground track for the evening of
> January 2nd over New Jersey! For example, there may have been
> pyro bolts or other deployment hardware related to the launch that
> would have had different drag coefficients, causing them to reenter
> earlier or later than the rocket body. Great idea on paper; alas,
> there were no passes close to New Jersey in the hours prior to
> 9pm on Tuesday night.
>
> --Rob
>
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Received on Fri 05 Jan 2007 08:10:41 PM PST