In Situ Detection of Organics on Mars

Jennifer Eigenbrode, Andrew Steele, Roger Summons, Amy McAdam, Brad Sutter, Heather Franz, Caroline Freissinet, Maeva Millan, Danny Glavin, Doug Ming, Rafael Navarro-Gonzales, Pan Conrad, Paul Mahaffy, the SAM and MSL teams

NAS SSB Search fro Life Across Time and Space • The SAM instrument and background signals • In situ detection of refractory organic matter via EGA • In situ identification of molecules via GCMS • Comparison to Tissint martian meteorite

SAM measurements of organic volatiles from sample Gas chromatograph Gas release trap sniff

Mass spectrometer

Oven

300 400 500 600 700 800 900

2. Gas chromatography1000

1. Evolved gas analysis (EGA) mass spectrometry (GCMS)

 Bulk gas evolution Molecular separation x 20 

1 and identification

Intensity Intensity 10 Intensity Intensity

Sample temperature in oven  0 GC retention time  What happens to a sample when its heated

under helium?

thermal pyrolysis

desorption Relative abundance Relative What happens to a sample when its heated under helium? thermal desorption O2 release from 2 O minerals leads to combustion of gas phase organics and CO2 release

pyrolysis Relative abundance Relative Macromolecules

Killops and Killops, 1993

Character of SAM background in Evolved Gas Analysis (EGA)

CO2

CH4 C4H8+ Higher confidence that organic signals are indigenous to sample

m/z and scaling factor Relative abundance Relative

The transition is dependent on sample chemistry Rocknest

Eigenbrod High temperature release from refractory organic matter CH4

C3-4 alkyl Relative abundance Relative Rocknest Eolian Drift Eigenbrode et al, 2014 AGU Fall Meeting - Gale Crater floor Eigenbrode et al., in prep

- scoop site, first analysis by SAM NASA/JPL-Caltech/MSSS Chemical composition of Gale, Meridiani and Gusev soils are basaltic and nearly identical in APXS measurements

• Global signature • Composition suggests limited chemical weathering (Berger et

al., 2013, JGR) Wt. % Wt.

Chemical components Yen et al., 2013, LPSC #2495; Blake et al. 2013, Science. MSL Team’s stratigraphy column (Grotzinger et al, 2015)

Pahrump Hills/Marias Pass Confidence Hills

Mojave2

Telegraph Peak

Murray fm. fm. Murray Buckskin

. . Yellowknife Bay

Mbr Cumberland

Mudstones John Klein Sheepbed Point Lake

Gillespie Lake Cumberland Sheepbed mudstone John Klein

Chlorinated C1-C4 chains and benzene detected

Yellowknife Bay - Gale Crater floor sediments Freissinet et al., 2015, - drill sites analyzed by SAM JGR - lake deposit (Grotzinger et al., 2015, Science) NASA/JPL-Caltech/MSSS SAM EGA of Cumberland Single-Ring Aromatic Hydrocarbons

m/z and scaling factor

+ +

CH O CH + 3 + + 2

CH CH 2 2

Relatively weak signals

Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep SAM EGA of Cumberland C1-C4 Alkyl Hydrocarbons

m/z and scaling factor

C1 Example carbon chain

C3 Relatively weak signals C4

Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep From refractory organic matter to chlorohydrocarbons proposed mechanism: Fenton-like reactions

Ionizing radiation + Organics + Metal catalysts

Low temperature evolution of chloro-hydrocabons may be an indication of radiolytic weathering Buckskin Telegraph Peak

Mojave Confidence Hills

Murray Formation at Pahrump Hills - bottom of Lower Mound outcrop at Gale Crater - drill sites analyzed by SAM - lake deposit (Grotzinger et al., 2015, Science) NASA/JPL-Caltech/MSSS SAM EGA of Mojave2

m/z and C1-C5? Alkyl Hydrocarbons scaling factor

Example carbon chain

Relative Relative C2 counts per second per counts

C4 C5? Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep SAM EGA of Mojave2 Single-Ring Aromatic Hydrocarbons

m/z and

Scaling factor

Cl + +

+ O CH3 CH + Relative Relative 2 + +

counts per second per counts CH2 CH2

Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep SAM EGA of Mojave2 Organic sulfur volatiles

Methanthiol

Dimethylsulfide

Relative Relative Thiophene counts per second per counts

Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep Identification of Organic Sulfur Compounds by SAM GCMS of Mojave2

60006000

50005000

40004000

1000)

x 30003000

20002000

(cps (cps

Response MS Response MS Relative MS MS Relative 10001000 MJ2 0 0 30030040040050050060060070070080080090090010001000CB_Blank2 Retention Times s (seconds) Comparison to Martian meteorites Example: Tissint Lab EGA analysis of Tissint martian meteorite C1-C4 Alkyl Hydrocarbons m/z and scaling factor Single-Ring Aromatic Hydrocarbons

C1 Organic sulfur volatiles

O +

CH2 + + C3

CH2 CH2 C4 Thiophene

Similar high temp release and composition as in situ Mars signals Eigenbrode et al, AGU, 2015 Eigenbrode et al., in prep Conclusions

• Refractory organic matter is present in the Rocknest eolian sediments and some lacustrine mudstones in Gale Crater

• Possible sources: • Abiotic igneous/hydrothermal? • Meteoritic? • Heavily processed biological?

• We don’t know the organic source. Could be a mixture.

Implications

• Organic matter may be widely distributed over the surface and throughout the rock record of Mars

• Supports habitability of the ancient lake environment in Gale Crater ~3.6 billion years ago  Organic molecules = energy and C source for metabolisms

• Supports modern and future habitability

Questions?