# Presentation: 054883

## SEDIMENTARY  ROCKS  AND  METHANE –

**SEDIMENTARY  ROCKS  AND  METHANE –**
**SOUTHWEST  ARABIA  TERRA**

**Carlton  Allen  and  Dorothy  Oehler**
**NASA  Johnson  Space  Center**
**Houston,  TX**
**Elizabeth  Venechuk**
**Scripps  College**
**Claremont,  CA**

## 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.**** **

## 800+ m  of  layered  sedimentary  rock  in  SW  Arabia  Terra  and  Sinus  Meridiani

**Edgett, 2005**

**800+ m  of  layered  sedimentary  rock  in  SW  Arabia  Terra  and  Sinus  Meridiani**

## Proposed  MSL  landing  sites

**Proposed  MSL  landing  sites**

## Our  proposed  landing  site

**Our  proposed  landing  site**

## Lat  6 N

**Lat  6 N**
**Long  356**

**Edgett, 2005**

## 55 km  diameter

**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.  

**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.**

## 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.  

**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 !**

## Slide 18

## S A M:

**S A M:**
**Detect  and  quantify  methane  << 1 ppb**
**Detect  and  quantify  heavier  hydrocarbons  ~ 1 ppb**
**Determine  carbon  isotope  ratios**

## 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  ********13C  distinguishes  between  microbial  sources  and  abiogenic  sources.  **
**(Allen, M. *****et al*****, 2005)**

## Enhanced  methane  concentrations  have been  measured  by  the  Planetary  Fourier  Spectrometer  on  Mars  Express.

## These  concentrations  were  reported  above  Arabia  Terra,  Elysium  Planum,  and  Arcadia-Memnonia.  	

**These  concentrations  were  reported  above  Arabia  Terra,  Elysium  Planum,  and  Arcadia-Memnonia.  ****	**
**	****Potential  source  areas ?**
**	****Higher  concentrations  to analyze.**

**Elysium**

**Arabia**

**Arcadia**

## 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.****       **