[meteorite-list] [meteorite-list]Response to: Mars Meteorite May Or May Not Show Signs Of Life; Four-Year Debate Continues

From: EKGMARS_at_aol.com <EKGMARS_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:44 2004
Message-ID: <cc.12cfdfa9.27f53f57_at_aol.com>

Regarding the posting by Ron Baalke on the article from the Dallas Morning
News on the controversy over evidence of possible Mars life, I feel that I
must respond. It must be noted that magnetites crystals produced in the
laboratory by the Golden et al. and reported in American Mineralogist are not
 identical to those reported by Kathie Thomas-Keprta et al. and the original
JSC Mars Meteorite Research Team. The Golden et al. laboratory study may be
an interesting laboratory study using pure inorganic chemical reagents and
unusual heating conditions, but it does not reproduce most of the unique
features identified within ALH84001 or the processes which operated on the
sample on Mars prior to its ejection from the surface of Mars. However, the
Golden et al. team have not shown that their magnetite crystals are identical
to the unique biogenically produced magnetites (which make up only 25% of the
magnetites within ALH84001). Thomas-Keprta et al. showed in their Geochimica
et Cosmochimica Acta manuscript in December 2000 and also in the February
2001 issue of the Proceedings of the National Academy of Sciences that the
unique magnetites produced by biogenic processes (i.e. magnetotactic
bacteria) have five unique properties identified to be the results of the
Darwinian selection rules.
    Thomas-Keprta et al. (2001) showed the intracellular magnetite crystals
produced by magnetotactic bacterium strain MV-1 display six distinctive
properties: (i) narrow size-range (i.e., single-domain for uniform
magnetization) and shape (restricted width-to-length (W/L) ratios); (ii)
unusual chemical purity (i.e., no trace elements or contamination by other
elements within the pure magnetites); (iii) few crystallographic defects;
(iv) an unusual truncated hexa-octahedral morphology; (v) elongation along
the [111] crystallographic axis; and (vi) alignment in chains within cells.
The characteristics are the result of biochemical and genetic control by the
organism and are consistent with natural (Darwinian) selection to maximize
the magnetic dipole moment of the individual magnetite crystals as well as
that of the entire cell. These characteristics can be used to define a
terrestrial biosignature. A biosignature is useful only if it is not
produced by a natural inorganic processes; that is, one that does not happen
through random, stochastic interactions or is not a product of directed human
intervention, which is better described as a synthetic inorganic process.
    The subpopulation of magnetites (approximately one quarter of the
magnetites within the carbonate globules) within ALH84001 which are suggested
to have a biogenic origin, meet five of these criteria (Note: the JSC team
have not reported on criteria (vi) which is the chain of magnetites within
the cells. At the 2001 LPSC in Houston and in the February issue of the
Proceedings of the National Academy of Sciences Friedmann reported "chains"
of magnetites within carbonate globules of ALH84001). No published reports
of inorganic "MV-1-like" truncated hexa-octahedral magnetites are known. The
magnetites produced in the laboratory by Golden et al. have been shown by
Thomas Keprta et al. at the recent LPSC to have an apparent simple octahedron
structure and are not the unique truncated hexa-octahedral structure which
appears to be a unique biomarker. In fact, the Golden et al. magnetites
appear to meet only two of the six Darwinian selection criteria. Because
every investigator accepts the fact that the magnetites were produced on
Mars, the unique truncated hexa-octahedral magnetites are a true biosignature
and probably constitute evidence of the oldest life (i.e. 3.9 billion years
old) yet found and that life resided on Mars!
    Everett Gibson
Received on Thu 29 Mar 2001 08:45:59 PM PST