[meteorite-list] Re: Mercury Meteorite Puzzle

From: Robert Verish <bolidechaser_at_meteoritecentral.com>
Date: Thu Apr 22 10:04:49 2004
Message-ID: <20020516194807.11374.qmail_at_web10407.mail.yahoo.com>

"NWA 011 has an oxygen isotope ratio that indicates it
came from a body larger than a big asteroid."

Okay. This article explains to me why this meteorite
came from a body larger than an asteroid. But it
doesn't explain how the other "planet-sized bodies" in
our solar system are being ruled-out in favor of
Mercury.

Is there an upper limit for the suspect "planet-sized"
parent body, that would exclude Mars, Venus, or Earth!
(The 81Kr-Kr age for NWA011 is 39 ± 5 Ma, which can be
interpreted as an upper limit of the cosmic-ray
exposure age, which would exclude the proto-versions
of these inner planets)?

Same-sized planetary bodies? We know enough about the
Moon to rule out a Lunar-origin, but do we know enough
about the Galilean moons of Jupiter to rule them out?

It would be interesting to see a matrix showing
suspect parent bodies vs. NWA 011 data, and to see
which evidence favors which "planet-sized body".

Here's what we already know:

April12th issue of Science, Akira Yamaguchi (National
Institute of Polar Research, Tokyo)
<http://www.sciencemag.org/cgi/content/short/296/5566/334>

Meteoritical Bulletin 84, Table 9

----------------------------------
[meteorite-list] MAPS and Mercury

Bernd Pauli HD bernd.pauli_at_lehrer1.rz.uni-karlsruhe.de

Sun, 14 Apr 2002 15:20:10 +0200

Marco wrote:

> By the way, I remember that some time ago a paper on
the characteritsics and expected numbers of meteorites
from several parent bodies (including Mercury and
Venus) has been published in Meteoritics & Planetary
Science.
> Sorry I do not have an exact reference ready at the
moment: that's because I am packing up to move to
another house currently. But a search on NASA ADS will
probably reveil it to you.


LOVE S.G. et al. (1995) Recognizing mercurian
meteorites (MAPS 30-3, 1995, 269-278).

ROBINSON M.S. et al. (2001) Ferrous oxide in Mercury's
crust and mantle (MAPS 36-6, 2001, pp. 841-847).

Best regs,

Bernd
-------------------------------------------

[meteorite-list] Mercury Meteorite Puzzle

Ron Baalke baalke_at_zagami.jpl.nasa.gov
Thu, 16 May 2002 10:38:56 -0700 (PDT)

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1991000/1991394.stm

Mercury meteorite puzzle
               
Is this from Mercury, the planet closest to the Sun?

By Dr David Whitehouse
BBC News
May 16, 2002

The first meteorite that may have come from Mercury
has been identified.

NWA 011 was found in the Moroccan Sahara in December
1999 and was immediately regarded as something
unusual.

It clearly had a molten past and was formed from
lighter materials than most meteorites. This implied
it had once been part of a much larger body.

It was originally classified as a eucrite, a group of
meteorites thought to be from the asteroid Vesta. But
a detailed analysis of NWA 011 showed it to be
different.

Now, researchers speculate that it is the first known
meteorite from our Solar System's innermost planet,
Mercury.

Rocks blasted off Mercury by a large impactor would
have a difficult journey to reach the Earth, say the
researchers - but not impossible. Nevertheless, the
calculations show such rocks would be an extremely
rare find on Earth.

NWA 011 has an oxygen isotope ratio that indicates it
came from a body larger than a big asteroid. Japanese
researchers say the basalt in NWA 011 suggests the
body from which it did originate had a core of molten
iron with an outer covering of silicon and aluminium
that formed a basaltic crust.

And that means a planet-sized body. Could it really be
Mercury?
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Received on Thu 16 May 2002 03:48:07 PM PDT