Good summaries and reviews of the results of the MER rover Mars missions.

Mostly about the Spirit mission at Gusev crater:

Remote Sensing Tutorial Page 19-13a
Missions to Mars during the Third Millenium
http://rst.gsfc.nasa.gov/Sect19/Sect19_13a.html

and:

Remote Sensing Tutorial Page 19-13b
http://rst.gsfc.nasa.gov/Sect19/Sect19_13b.html

which is mostly about the Opportunity mission at Meridiani.

This second also has a link to a report that might offer an
explanation for the lack of carbonates at the Meridiani landing site:

ACID SEDIMENTARY ENVIRONMENTS ON MARS?: POSSIBLE TERRESTRIAL ANALOGS
http://gsa.confex.com/gsa/2002AM/fin...ract_36936.htm



Bob Clark

"Robert Clark" wrote in message
om...


This second also has a link to a report that might offer an
explanation for the lack of carbonates at the Meridiani landing site:

ACID SEDIMENTARY ENVIRONMENTS ON MARS?: POSSIBLE TERRESTRIAL ANALOGS
http://gsa.confex.com/gsa/2002AM/fin...ract_36936.htm


Meridiani is a hydrothermal system, not an acid lake. Hot springs
have a very high biological potential and are thought to be the source of the
first life on earth. The sulfates are a byproduct of bacteria, not
a salty sea. And this type of hematite is formed in /hot water/.
And the notion no carbonates have been found is incorrect.
Please look at the mossbauer charts below for yourself.



Morphological Biosignatures and the Search for Life on Mars

"Determining the location of potential paleobiological repositories
on Mars requires an understanding of the martian surface in
terms of elemental abundances and mineralogy. This variety
of hematite on Earth forms only in the presence of large amounts of
water, and typically at elevated (hydrothermal) temperatures
(Christensen et al., 2000)."
http://geology.asu.edu/jfarmer/pubs/pdfs/morpho.pdf


"It is this common association of microbes and iron
deposition on earth that has spurred hopes that robot
crafts exploring the hematite anomaly of Mars' Meridiani
Planum might find evidence for ancient life. The
hematite deposits of Meridiani Planum [7], regardless of
their exact origin, are considered to be a favorable host
for microorganisms that might have been associated
with their formation [8]."
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/1369.pdf








A Bowl of Hematite-Rich 'Berries'
Mar 18, 2004

"This graph shows two spectra of outcrop regions near the
Mars Exploration Rover Opportunity's landing site.
The blue line shows data for a region dubbed "Berry Bowl,"
which contains a handful of the sphere-like grains dubbed
"blueberries."

Blueberry Bowl chart
http://www.jpl.nasa.gov/mer2004/rove.../image-19.html





A Mossbauer investigation of iron-rich terrestrial
hydrothermal vent systems: Lessons for Mars exploration

Jack D. Farmer
NASA Ames Research Center, Moffett Field, California

"Currently, Jack is the Director and Principal Investigator of the NASA funded
Astrobiology Program at Arizona State University, he leads the NASA
Astrobiology Institute's Mars Focus Group and is on the Executive
Board of the NASA Astrobiology Institute. He holds appointments
on various NASA committees including the....."
http://geology.asu.edu/jfarmer/biography/pro.html


Stromatolite Chart
(Fig 26, page 16)
http://geology.asu.edu/jfarmer/pubs/pdfs/mossbauer.pdf


4. Siderite as a Component of an Ancient Stromatolite

"Mossbauer spectra at two temperatures of a freshly slabbed
portion of a 2.09 Ga (Early Proterozoic) hematic chert stro-
matolite from the Gunflint Iron Formation (PPRG 2443) are
shown in Figure 26. The high-velocity ferrous peak migrates
from its position at 100 K to overlap the fifth peak of hematite
at 19 K. This behavior and the agreement of the splitting pa-
rameters with those of siderite argue that this sample contains
a small fraction of siderite. (dominant siderite peak at -1090 cm-I).
The sample investigated was freshly slabbed for the Mossbauer
transmission measurement, so the iron carbonate is interior
to the native stromatolite rock. Its occurrence in this 2.09 Ga
old rock in- dicates that long (billion-year) survival times
for siderite are possible when preserved in silica."











Bob Clark

"Robert Clark" skrev i en meddelelse
om...

snip

This second also has a link to a report that might offer an
explanation for the lack of carbonates at the Meridiani landing site:

ACID SEDIMENTARY ENVIRONMENTS ON MARS?: POSSIBLE TERRESTRIAL ANALOGS
http://gsa.confex.com/gsa/2002AM/fin...ract_36936.htm

Your link makes me wonder...
As a geologist, like the rest of you, I know geology primarily from the
leftovers/scrape off and very seggregated mainly siliciclastic, aluminous
(clay) and their volcanic and metamorpnic eqvivalent rock that is a result
of largescale processes working over time. We have silicious continental
crust where we reign and basaltic oceanic crust deep below the watersurface.
Mars does not display the same kind of seggregation and I wonder if the
consequence could be that the environment can be thought of as a shallow sea
on oceanic crust. It sounds straight and self-evident, but I don't think
that there is Earth analogs. The salty sabka/desert environment may put some
morphology into sediments present. As for the chemistry hydrothermal,
without thermal, could be appropriat.
Seeing fluvial structures on top with flat fine stratification below may
have a straightforward association to increasing waterdepth where sediments
can settle out in undisturbed fine layers
I've been looking out for sabka faciesassociations and found an Anatolian
example

http://journals.tubitak.gov.tr/earth...1-2-0004-1.pdf

Basalts/pyroxenes and not silicious sand/fines may be available in a
basalt-sabka, and the sediment may be expected to shallow upward
proportional to a developement of evaporites. It makes some sense.

Carsten