Chemistry ModelsChemistry Models

Yuk YungYuk Yung

GPS CaltechGPS Caltech

Sagan Exoplanet Summer Sagan Exoplanet Summer WorkshopWorkshopJul 20 2009Jul 20 2009

ModelsA

Common photochemistry: hundreds of molecules, thousands of reactions

Transport: 1-D diffusion vertical

2-D advection

3-D general circulation model

Yung and DeMore, 1999

Jupiter: The cosmic reference pointJupiter: The cosmic reference point

Titan: Nature’s Laboratory of Organic Synthesis Titan: Nature’s Laboratory of Organic Synthesis

Mars: Is Methane biologically produced?Mars: Is Methane biologically produced?

Earth: The cosmic end memberEarth: The cosmic end member

Conclusions Conclusions

Today’s OutlineToday’s Outline

Gravity and EscapeGravity and Escape

Yung and DeMore, 1999

Determines EvolutionDetermines Evolution

77

Amino acids

Proteins(Catalysts)

Fatty acids Nucleotides

Lipids(Membranes)

Nucleic acids(Information)

PurinesPyrimidines

Sugars

The chiral Molecules of LifeThe chiral Molecules of Life

Jupiter: The cosmic reference pointJupiter: The cosmic reference point

Titan: Nature’s Laboratory of Organic Synthesis Titan: Nature’s Laboratory of Organic Synthesis

Mars: Is Methane biologically produced?Mars: Is Methane biologically produced?

Earth: The cosmic end memberEarth: The cosmic end member

Conclusions Conclusions

Today’s OutlineToday’s Outline

Hydrocarbons

Winter Circulation

Hydrocarbon Gradients

21

C2H2 Abundance

Photochemical results

Liang et al. 2007

CH4; hydrostatic

CH4; non-hydrostaticHC3N

HCN

C6N2

C6H6 C6N2; condensation line

Mars: Gone with the (Solar) WindMars: Gone with the (Solar) Wind

Isotopic FractionationIsotopic Fractionation

Kass and Yung Science 1995Kass and Yung Science 1995Kass and Yung Science 1995Kass and Yung Science 1995

Jupiter: The cosmic reference pointJupiter: The cosmic reference point

Titan: Nature’s Laboratory of Organic Synthesis Titan: Nature’s Laboratory of Organic Synthesis

Mars: Is Methane biologically produced?Mars: Is Methane biologically produced?

Earth: The cosmic end memberEarth: The cosmic end member

Conclusions Conclusions

Today’s OutlineToday’s Outline

Escape and Rayleigh DistillationEscape and Rayleigh Distillation

Methane on Mars

* Spectroscopic detection* Biological Production ? * Geochemical Sources ?

Mumma et al. 2009

(Nair, Summers, Miller, and Yung, ICARUS, 2005)

INMS

SOIR

This shows the residual circulation of the stream function. The solid lines represent a clockwise flow and the dotted a counterclockwise flow. The top left graph is for January, the top right for April, the bottom left for July, and the bottom right for October.

This is a 3D representation of the methane concentration on Mars for the BASE model simulation for months 36 to 54. It is evident that the most change occurs in the southern polar regions.

This shows the Methane concentration for 6 boxes in the troposphere. Of particular interest is the top left graph, which represents the Southern pole where the concentration changes dramatically as a result of condensation and evaporation of Carbon Dioxide.

The Earth produced hydrogenfrom some of this water

H2

volcano

Cf. Anatahan, N Marianas (Credit: A. Sauter).

Carbon dioxide exhaled from volcanoes in single-passmagma-transfer to produce the early atmosphere

CO2 >> S8, NO

So the atmosphere was carbon dioxide (CO2)

The atmosphere was carbon dioxide (CO2)

and the ocean was carbonated water,

i.e. acidic (pH 5.5)

4H2 + 2CO2 CH3COOH + 2H2O

& 4H2 + CO2 CH4 + 2H2O

Hydrogen plus carbon dioxidereact slowly to producemethane or acetate

Reactions that are quickened to LIFE

Exothermic and

From W. Bach

OceanAcidic on-axis400C springsFe,Zn,Ni,Co

Dudley Foster (WHOI)National GeographicNovember 1979,

Too hot,too acidic,too oxidized & too spasmodic(melting point oflead is 327.5ºC)

Exothermic and

From W. Bach

Main energy dischargeat alkaline off-axis site

Ocean

ALKALINE SUBMARINE SPRINGCaCO3

Mg(OH)2

pH 11 T 91C

H2 15mmol

~100,000 years

Kelley et al. 2001, Nature 412, 145Science 2005, 307Früh-Green + 2003, Science 301, 495Ludwig et al. 2005EOS, 86,V51B-1487

compartments

Martin et al. Nature Microbiol Rev 6, 805

credit: Deb Kelley

Lost City Abiotic H2 >

CH4 > HCOO- > CH3COO-

Serpentinization Reactions

+ CHOO-

+formate

120ºC

90ºC

40ºC

Boetius, 2005 Science, 307, 1420

+ CHOO-

Früh-Green et al., 2003 Science 301, 495

3MgFeSiO4 + 4H2O 3SiO2 + Fe3O4 + 3Mg2+ +6OH- + H2

Serpentinite

State rock of California

overall reaction:

olivine + water magnetite + serpentine + alkali + H2

Mg2.85Fe0.15Si2O5(OH)4

3MgFeSiO4 + 4H2O 3SiO2 + Fe3O4 + 3Mg2+ + 6OH- + H2

Bach et al. 2006 Geophys. Res. Lett, 33, L1330

and CH4 > HCOO- > CH3COO-

Geochemicalpath

Can the geochemical pathbe quickened through anFeS membrane?

Recast from Maden 2000Biochem. J. 350, 609

40 mm

Na2S

FeCl2

FeCl2

Na2S

FeS

FeS compartments

‘HadeanOcean’

Forced injection

“seep”

Simulation of an alkaline seepage into acidulous ocean

FeS

‘crust’

Jupiter: The cosmic reference pointJupiter: The cosmic reference point

Titan: Nature’s Laboratory of Organic Synthesis Titan: Nature’s Laboratory of Organic Synthesis

Mars: Is Methane biologically produced?Mars: Is Methane biologically produced?

Earth: The cosmic end memberEarth: The cosmic end member

Conclusions Conclusions

Today’s OutlineToday’s Outline

Li et al. PNAS 2008

Habitable Zone

Earth (Snowball, Gaia Lifeboat)Earth (Snowball, Gaia Lifeboat)

Liang et al. PNAS 2007

Li et al. PNAS 2009 (in press)

O3

H2O

H2O

CO2

Absorption in Earth’s Atmosphere

Li et al. PNAS 2009 (in press)

Extending the Lifespan by Regulating Pressure

Li et al. PNAS 2009 (in press)

Testable Hypothesis

Planets have evolved

Isotopic composition provides clues

Look of life supporting chemistry

Conclusions:ChemistryConclusions:Chemistry

ThanksThanks

Yung’s Group at Caltech,Yung’s Group at Caltech,Liang (Taiwan), Jiang (U Houston)Liang (Taiwan), Jiang (U Houston)Lunine’s book 2004Lunine’s book 2004Prof Michael RussellProf Michael RussellNASA/JPLNASA/JPLNSFNSFESAESA