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"Robert Clark" <rgregoryclark@xxxxxxxxx> wrote in message
news:1157584537.471807.263540@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Just saw this on Unmannedspaceflight.com:
Mineralogy of the light-toned outcrop at Meridiani Planum as seen by
the Miniature Thermal Emission Spectrometer and implications for its
formation.
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, E12S03,
doi:10.1029/2005JE002672, 2006
"Abstract
Analysis of Miniature Thermal Emission Spectrometer (Mini-TES) data has
led to the recovery of a pure end-member spectral shape related to the
light-toned outcrop observed at Meridiani Planum. Data from the MER
Mössbauer spectrometer, APXS, and previous Mini-TES measurements were
used to constrain a spectral library used to determine the mineralogy
of the outcrop from this spectral shape. Linear deconvolution of the
outcrop spectral shape suggests that it is composed primarily of
Al-rich opaline silica, Mg-, Ca-, and Fe-bearing sulfates, plagioclase
feldspar, nontronite, and hematite. Conversion of modeled mineralogy to
chemistry shows good agreement with the chemical composition of the
outcrops determined by APXS. Details of the analysis procedure and
implications for the formation of the outcrop are discussed along with
terrestrial analogs of the ancient environment at Meridiani."
http://www.gps.caltech.edu/~tglotch/2005JE002672.pdf
According to the authors the spectra of the Meridiani bedrock is best
matched by a composition that includes 10% nontronite clay.
Bob Clark
So that would mean a less acidic environment that is more friendly
to life I believe. All those layered rocks and outcrops were formed
by evaporation of shallow seas and weathered by water.
Doesn't this paint a picture of Mars that has substantial underground
water that flows to or near the surface periodically? Alternating wet
and dry periods. Perhaps as ice ages wax and wane?
The article also claims that water is about 5% by weight of the outcrops.
It's starting to look like water, not volcanism, is the more active
weathering process.
The idea that Mars has been dry for geologic time just doesn't
sound anything at all like the truth. Does anyone know how
long Mars ice ages last? I'd suspect they'd be rather
chaotic with the complicated orbit.
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