Thiago Altair, Marcio G. B. de Avellar, Fabio Rodrigues, Douglas Galante
The Importance of Radioactive Sources for the Origin of Life and the Habitability of Icy
Moons in the Solar System
AstrobiON / October 2018
Environmental and Planetary Sciences
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BiosignaturesDetection and characterization of life
BiosignaturesDetection and characterization of life
Molecular
BiosignaturesDetection and characterization of life
Molecular
Mineral
BiosignaturesDetection and characterization of life
Molecular
Mineral
Morphological
BiosignaturesDetection and characterization of life
Molecular
Mineral
Morphological
How did this all begin?
Some very old forms of life...
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1 µm
Mink Mountain Gunflint chert
Vida ?
Life’s building blocks
Life’s building blocks
Life’s building blocksWater
Nucleic acids
Aminoacids
Lipids
Carbohydrates
Life’s building blocksWater
Nucleic acids
Aminoacids
Lipids
Carbohydrates
CHONPS
Life’s building blocksWater
Nucleic acids
Aminoacids
Lipids
Carbohydrates
CHONPS+ disequilibrium
Extraterrestrial life
Geological time
A planet of bacteria
A planet of bacteria
A planet of bacteria
SECO
SECO
Extremophiles
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The deep environment of icy moons
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The deep environment of icy moons
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The deep environment of icy moons
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The deep environment of icy moons
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The deep environment of icy moons
12Galileo old data reanalysed (2018) ! Europa plumes!
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Europa Clipper / JUICE
Europa
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Europa• Icy moons: We can find liquid water in abundance, mesophilic
temperatures. The oceans under the icy crusts may present biophilic environments.
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Europa• Icy moons: We can find liquid water in abundance, mesophilic
temperatures. The oceans under the icy crusts may present biophilic environments.
• Exogenous and endogenous sources of energy
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Europa• Icy moons: We can find liquid water in abundance, mesophilic
temperatures. The oceans under the icy crusts may present biophilic environments.
• Exogenous and endogenous sources of energy
• Source of biological energy: direct radiolysis of water by primordial radioactive elements accumulated in these moons in the beginning of the Solar System history.
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Europa• Icy moons: We can find liquid water in abundance, mesophilic
temperatures. The oceans under the icy crusts may present biophilic environments.
• Exogenous and endogenous sources of energy
• Source of biological energy: direct radiolysis of water by primordial radioactive elements accumulated in these moons in the beginning of the Solar System history.
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We perform a thermodynamic analysis to demonstrate that it would be possible to attain
enough chemical energy to sustain na extremophilic ecosystem.
Motivation: natural nuclear reactors
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Motivation: natural nuclear reactors
3Gyr ! ~3% U235
Oklo
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Motivation: natural nuclear reactors
3Gyr ! ~3% U235
Oklo
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Water radiolysis
thorianite
uraninite
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Water radiolysis
thorianite
uraninite
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α
γ
β
Water radiolysis
thorianite
uraninite
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α
γ
β
Water radiolysis
𝐹𝑒𝑆2 + 4𝐻𝑂• → 𝐹𝑒2+ + 𝑆 + 𝑆𝑂−24 + 2𝐻2
thorianite
uraninite
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α
γ
β
Sulfate biochemistry
4𝐻2 + 𝐻+ + 𝑆𝑂2−4 → 𝐻𝑆− + 4𝐻2𝑂
Desulfovibrio vulgaris
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A special extremophile
• Mponeng gold mine in South Africa
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation• 60 °C and pH of 9.3
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation• 60 °C and pH of 9.3• Single species ecosystem
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation• 60 °C and pH of 9.3• Single species ecosystem• Radiophilic (?!) bacteria
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A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation• 60 °C and pH of 9.3• Single species ecosystem• Radiophilic (?!) bacteria
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Julio Verne’s Journey to the Center of the Earth
Descende, audax viator, et terrestre centrum attinges (Descend, bold traveller, and you will attain the center of the Earth)
A special extremophile
• Mponeng gold mine in South Africa
• 2.8 km deep• Gram positive sulfate-
reducing bacterium• Carbon and nitrogen fixation• 60 °C and pH of 9.3• Single species ecosystem• Radiophilic (?!) bacteria
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Julio Verne’s Journey to the Center of the Earth
Descende, audax viator, et terrestre centrum attinges (Descend, bold traveller, and you will attain the center of the Earth)
A special extremophile
A survivor from the LHB?
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D.Audaxviator metabolism
A simplified metabolism
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Radiolysis modelling for Europa
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Radiolysis modelling for Europa
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1) Metabolism of Desulforudis audaxviator
2) 238U, 232Th, 40K abudances for radiolysis
3) Experimental rate of production of SO42− via oxidation of
pyrite
! Europan deep ecosystem carrying capacity
(⋆) Here we are exploring an internal souce for SO42−, not
exogenous.
Radiolysis modelling for Europa
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The rate of production of this anion via radiolysis is given by
Where
• Gs = 2.1 × 10−9 mol/m2/(J/kg) (experimental value) is the efficiency of the sulfate production via radiolysis ;
• Di =EiλiciNaA−1 [J/kg/year] is the radiation dose rate for the various species i;
• E [J /decay ] is the energy per decay corrected by neutrino loss ; • λ = 1/t1/2 [decay /year ] is the decay constant; • c [ppm] is the concentration of the radioactive element ; • Na = 6.022 × 1023 is the Avogadro’s number ; • A [g/mol] is the atomic mass
𝒀 = ∑𝒊
𝑫𝒊 × 𝑮𝒔
Radiolysis modelling for Europa
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The rate of production of this anion via radiolysis is given by
Where
• Gs = 2.1 × 10−9 mol/m2/(J/kg) (experimental value) is the efficiency of the sulfate production via radiolysis ;
• Di =EiλiciNaA−1 [J/kg/year] is the radiation dose rate for the various species i;
• E [J /decay ] is the energy per decay corrected by neutrino loss ; • λ = 1/t1/2 [decay /year ] is the decay constant; • c [ppm] is the concentration of the radioactive element ; • Na = 6.022 × 1023 is the Avogadro’s number ; • A [g/mol] is the atomic mass
𝒀 = ∑𝒊
𝑫𝒊 × 𝑮𝒔
The annual production of radiolitic sulfate is given by Ps = Ys × Spy, where Spy [m2/kgrock] is the surface area of pyrite per kilogram of sedimentary rock.
Results
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Our numbers are :
• 0.056 to 15 ppm of 232Th ; • 0.016 to 271 ppm of 238U ; • 380 to 3800 ppm of 40K;
*we assumed pyrite concentration of 5 wt.% and pyrite surface area of 1.13m2/kgrock
Results
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Our numbers are :
• 0.056 to 15 ppm of 232Th ; • 0.016 to 271 ppm of 238U ; • 380 to 3800 ppm of 40K;
*we assumed pyrite concentration of 5 wt.% and pyrite surface area of 1.13m2/kgrock
Europa?
Results
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Our numbers are :
• 0.056 to 15 ppm of 232Th ; • 0.016 to 271 ppm of 238U ; • 380 to 3800 ppm of 40K;
*we assumed pyrite concentration of 5 wt.% and pyrite surface area of 1.13m2/kgrock
Our result is, then,
Ps = 0.82 − 8.2 nM/year,
which is of the same order or one order of magnitude greater than the minimum necessary for the survival of the D.audaxviator.
(⋆) Important remark : models for the origin, composition and evolution of the crust and ocean of Europa suggest the formation of pyrite-like materials, being these a major component.
Europa?
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
Type of aggregat
eGrain d(µm)
Spy(d) (m2.kg-1)
Clay 2 1.41×103
Silt10 2.83×102
60 4.71×101
Sand125 2.26×101
500 5.651000 2.83
Pebbles 10000 2.83×10-1
50000 5.65×10-2
Cobbles 100000 2.83×10-2
200000 1.41×10-2
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
Close-packing modelGeological dependence of pyrite availability
In summary
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In summary
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• From calculation for Europa it is possilbe to provide at least as much energy as the necessary only by the γ decay of 40K since its abundance can be 10 times (or more) greater than that found on Earth oceans.
In summary
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• From calculation for Europa it is possilbe to provide at least as much energy as the necessary only by the γ decay of 40K since its abundance can be 10 times (or more) greater than that found on Earth oceans.
• This result makes Europa a propitious place for the development of an ecosystem that sustains simple forms of life like the sulphate-reducing bacteria Desulforudis audaxviator.
In summary
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• From calculation for Europa it is possilbe to provide at least as much energy as the necessary only by the γ decay of 40K since its abundance can be 10 times (or more) greater than that found on Earth oceans.
• This result makes Europa a propitious place for the development of an ecosystem that sustains simple forms of life like the sulphate-reducing bacteria Desulforudis audaxviator.
• Our results also make of Europa a good place for searches for extraterrestrial forms of life.
In summary
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• From calculation for Europa it is possilbe to provide at least as much energy as the necessary only by the γ decay of 40K since its abundance can be 10 times (or more) greater than that found on Earth oceans.
• This result makes Europa a propitious place for the development of an ecosystem that sustains simple forms of life like the sulphate-reducing bacteria Desulforudis audaxviator.
• Our results also make of Europa a good place for searches for extraterrestrial forms of life.
• Habitable zones extented to radioactive environments!
Fontes hidrotermais Origin of life?
Fontes hidrotermais Origin of life?
Fontes hidrotermais Origin of life?
Fontes hidrotermais Origin of life?
Fontes hidrotermais Origin of life?
Fontes hidrotermais Origin of life?
Sphere in movement
Example of equilibrium
Sphere in movement
Example of equilibrium
Sphere in movement
Example of equilibrium
Out of equilibrium
Example of equilibrium
Out of equilibrium
Example of equilibrium
Out of equilibrium
Example of equilibrium
Out of equilibrium
Example of equilibrium
Out of equilibrium
Example of equilibrium
Out of equilibrium
Example of equilibrium
Example of equilibrium
In equilibrium
Static equilibrium
Example of equilibrium
In equilibrium
In summary...Reactants Products
In summary...Reactants Products
Chemical equilibrium
In summary...Reactants Products
Chemical equilibrium
Important: From thermodynamics, the chemical equilibrium will only happen when the procces is not sponteneous in any direction!
If a system in equilibrium is disturbed by an alteration on concentration, temperature or pressure of one of its componentes, the system will move its equilibrium position in a way to balance the effects of perturbation.
Le Chatêlier principle
Henry Louis Le Chatêlier (1850-1936)
Químico francês
Lost Cityhydrothermal system
• Off-axis mid-ocean rige
• Moderate temperatures (~60 - 120oC)
• High pH (10): strong gradient
• Source of H2 and CH4
• Fe and S available • Microenvironment and
compartimentalization
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Lost Cityhydrothermal system
• Off-axis mid-ocean rige
• Moderate temperatures (~60 - 120oC)
• High pH (10): strong gradient
• Source of H2 and CH4
• Fe and S available • Microenvironment and
compartimentalization
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Volcanic CO2
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Volcanic CO2
H2 hidrothermal
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Global electrochemical cell
Volcanic CO2
H2 hidrothermal
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Global electrochemical cell
Volcanic CO2
H2 hidrothermal
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Natural radioactive environments as sources of local disequilibrium for the
emergence of life Thiago Altair, Larissa M. Sartori, Fabio Rodrigues, Marcio G.
B. de Avellar, Douglas Galante
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Natural radioactive environments as sources of local disequilibrium for the
emergence of life Thiago Altair, Larissa M. Sartori, Fabio Rodrigues, Marcio G.
B. de Avellar, Douglas Galante
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