SEDIMENTARY ROCKS AND METHANE

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SEDIMENTARY ROCKS AND METHANE SOUTHWEST
ARABIA TERRA
Carlton Allen and Dorothy Oehler NASA
Johnson Space Center Houston, TX Elizabeth
Venechuk Scripps College Claremont, CA
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The MSL Scientific Objectives for exploring
a site are to 1) assess the biological
potential, 2) characterize the geology and
geochemistry, and 3) investigate planetary
processes of relevance to past and present
habitability. On Earth sedimentary rocks
reveal the history of past environments and
contain the physical, chemical, and isotopic
biomarkers that provide evidence past life.
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800 m of layered sedimentary rock in SW
Arabia Terra and Sinus Meridiani
Edgett, 2005
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Proposed MSL landing sites
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Our proposed landing site
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Lat 6 N Long 356
Edgett, 2005
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55 km diameter 750 m deep
Edgett, 2005
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Methane has been detected in the martian
atmosphere at a concentration of 10 ppb.
The lifetime of methane against
decomposition by solar radiation is around
300 years, strongly suggesting that methane
is currently being released to the
atmosphere.
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By analogy to Earth, possible methane
sources on Mars include active volcanism
or hot springs, ongoing serpentinization of
basalt, thermally-matured sedimentary
organics, and living microbes. The
discovery of any one of these sources
would revolutionize our understanding of
Mars !
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S A M Detect and quantify methane ltlt 1
ppb Detect and quantify heavier hydrocarbons
1 ppb Determine carbon isotope ratios
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Confirm or refute methane detection Address
temporal and spatial variations in methane
abundance Address the methane source on
Earth correlation of the ratio of methane /
(ethane propane butane) with d13C
distinguishes between microbial sources and
abiogenic sources. (Allen, M. et al, 2005)
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Enhanced methane concentrations have been
measured by the Planetary Fourier
Spectrometer on Mars Express.
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Arcadia
Elysium
Arabia
These concentrations were reported above
Arabia Terra, Elysium Planum, and
Arcadia-Memnonia. Potential source areas
? Higher concentrations to analyze.
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MSL landing in SW Arabia Terra can address
the past biological potential, geology, and
geochemistry within 750 m of sedimentary
rock and improve analyses addressing the
detection, variations, and microbial vs.
abiogenic source of gases currently being
released from the martian crust.