Science > Physics > "Martian Soils Point to Ancient Acid Ocean--And a Dearth of Life."
| Topic: |
Science > Physics |
| User: |
"Robert Clark" |
| Date: |
30 Oct 2006 06:51:25 AM |
| Object: |
"Martian Soils Point to Ancient Acid Ocean--And a Dearth of Life." |
Martian Soils Point to Ancient Acid Ocean--And a Dearth of Life.
"Despite being separated by thousands of kilometers, Martian soils from
Gusev Crater and Meridiani Planum have proved broadly similar in
parts--rich in chlorine and sulfur. Recent high-precision measurements
have shown that phosphorus--the critical energy carrier in all known
forms of Earth life--is equally abundant in such patches of Martian
dirt. And the only explanation for such similar soils in disparate
locations is a large, acidic ocean, according to a new paper published
today in the November issue of Geology."
http://www.sciam.com/article.cfm?chanID=3Dsa003&articleID=3D000A1326-800A-1=
53E-800A83414B7F012F
The researchers discount the possibility of life because on Earth the
phosphorus found would be absorbed by life.
However, phosphorus is concentrated by clays which might account for
its concentrations:
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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Phosphorus and clays.
Posted by Robert Clark on 1/5/2005 6:55:02 AM
In Reply to: UPDATE: Wishstone Rich in Phosphorus posted by jms on
1/3/2005 3:14:19 PM
Clay is known to be highly absorptive of phosphorus because of its
small grain size.
Reducing phosphorus in aquatic systems using modified clays.
http://www.eidn.com.au/phos98.html
This page discusses the absorption of phosphorus on clays and other
sedimentary materials:
13.3 Binding of phosphorus in sediments.
http://lepo.it.da.ut.ee/~olli/eutr/html/htmlBook_98.html
However, I've been informed that the APXS, Pancam, and mini-TES do not
have sufficient resolution to see if the phosphorus is concentrated in
the dark, smooth inclusions.
But perhaps the mini-TES could measure them if it were placed closer to
the target rock than is usually done.
Bob Clark
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
http://www.habitablezone.com/space/messages/363979.html
Clays have been found at the Gusev site and a recent paper claims the
infrared spectra at Meridiani is best matched by a composition that
includes 10% clay:
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
M=F6ssbauer 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
It may be that life indeed was active in absorbing much of the
phosphorus but the amounts seen by the rovers is because of the
concentrating capacity of clays.
Bob Clark
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