THE OCEANS OF EUROPA AND GANYMEDE. AQUEOUS SOLUTION UNDER PRESSURE AS POTENTIAL HABITATS

O. Prieto-Ballesteros (1), V. Muñoz-Iglesias (1) and L. Jiménez Bonales (1, 2)

(1) Centro de Astrobiología. INTA-CSIC, Madrid, Spain

(2) Complutense University, Madrid, Spain

MOTIVATION There are some indirect evidences of the presence of liquid reservoirs in

the interior of Europa and Ganymede. There are no direct data about the characteristics of aqueous cryomagmas yet. Cryomagmatic processes have interest for Astrobiology because involve relative warm water rich liquids

Simulation experiments can provide some knowledge about the chemical reactions and geological processes that can be expected to occur at subsurface conditions

The information that we already have about the endogenic materials at the surface, the geochemical models of the satellite, and the geophysical models about the internal structure, are used for setting up the experiments

Experiments: Crystallization of gas clathrates from salty solutions Solubility of gases under pressure in salty solutions Processes of fractional crystallization of cryomagmasEvolution of aqueous liquids

Environmental constraints for habitability

CONSTRAINTSEUROPA Pressure. We consider a total

pressure range from 1 to 1800 bar, taking into account a water ice crust of 20km (≈240 bar) and a total water-rich layer of 100-150 km (cryomagmas ascend into the crust)

Temperature , dependent on the solution composition

Composition. We assume the aqueous composition is mainly sulfate rich, with CO2 (sulfuric acid and other salts are also considered)

EQUIPMENT

Two different high pressure chambers located at Centro de Astrobiología (CAB-INTA-CSIC), Madrid, are available for making these experiments: HPPSC (High Pressure Planetary Simulation Chamber),

which working pressure range is 1-3000bar (extendable up to 10000 bars), the sample volume is 10ml. It has four ports for making different in situ analysis, including sapphire windows for optical measurements

MPPSC (Moderate-high pressure Planetary Simulation Chamber), which maximum working pressure is 300bar, the volume is variable up to 50ml due to a mobile piston. It also has a window for spectroscopic measurements

Both chambers are made of stainless steel and have automatic control system for temperature and pressure. Raman and ultraviolet spectroscopy have been the main techniques used during the experiments.

HPPSCP

Hydrauliccompressor

Pressure transducer

HighPressureChamber

CO2

V1

V2

V3

Thermalfluid

Sapphire window

Thermocouple

Pressure transducer

P

Opticsystem

Laser CCD

Monochromator

Optic Fibers

MPPSC

CLATHRATE FORMATION FROM MGSO4 SOLUTIONS

There were not any experiment on CO2-clathrates formed from MgSO4-H2O in the literature

Salts are inhibitors of clathrate formation. Sulfates affects less than chlorides

Theoretical models shows a decrease of temperature of 3-4 degrees in the dissociation line

PROCEDURE FOR CLATHRATE FORMATIONClathrates are formed from a solution saturated in CO2 and different concentration of MgSO4 (5, 10, 17% weight)

Formation cycle: ABCD

Analysis of the kinetic of clathrate formation by Raman

Calibration: evolution of the brine using the SO4

2- peaks

1000 1500 2000 2500 3000 3500

0

500

1000

1500

960 970 980 990 1000 1010

0

500

1000

1500

Inte

nsi

ty (

a.u

.)

Raman Shift (cm-1)

2.5% 5% 7.5% 10% 13.5% 17%

RAMAN MONITORING OF CLATHRATE FORMATION

265 270 275 280 285 290 2950

20

40

60

80

100

10% MgSO4 exp

10% MgSO4 theor

H+I+CO2(g)

H+I+CO2(l)

H+Lw+CO2(l)

P (

bar)

T (K)

H+Lw+CO2(g)

EVOLUTION OF THE SOLUTION

900 1000 1200 1300 14000

1000

2000

30000

1000

2000

30000

1000

2000

SO2-4

Raman Shift (cm-1)

CO2 gas

Inte

nsi

ty (

a.u

.)

SO2-4

CO2 clathrate

CO2 dissolved

1000 1500 2000 2500 3000 3500

900 1000 1100 1200 1300 1400

Inte

nsi

ty (

a.u

.)

Raman Shift (cm-1)

1000 1500 2000 2500 3000 3500

900 1000 1100 1200 1300 1400

Raman Shift (cm-1)

CO2 bands (1280 and 1380 cm-1): Fermi bands are displaced, hot bands disappear

SO42- band change during the formation

of clathrates. It increases in the first moment, and finally decreases if saturation of the salt produce its precipitation

APPLICATION TO EUROPAFormation of clathrates in aqueous reservoir may produce the fractional differentiation of the cryomagmatic liquids

A: H2O-CO2-MgSO4 cryomagmatic chamber

B: CO2 clathrates crystallize

C: Brine concentrates and separates, salts can precipitate

D: Dissociation by P/T change. Clean H2O-CO2 cryomagmas can erupt

DCBA

SOLUBILITY OF CO2 IN SALTY SOLUTIONS

There are solubility data of CO2 in some brines at different pressures (chlorides, Na-sulfate) but not MgSO4 and just to relative high pressures

273 323 373 423 4730

2

4

6

8

10

mCO2=0.05 y mNS=1Linear (m-CO2=0.05 y mNS=1)mCO2=0.1 y mNS=1Linear (mCO2=0.1 y mNS=1)

Temperature (K)

Pre

ss

ure

(M

Pa

)

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

2

2.5

3

Solubility CO2 in a brine 12%Na2SO4

313

%w

ight

CO

2

Pressure (MPa)

273 323 373 423 4730

2

4

6

8

10

mCO2=0.05 y mNS=2Linear (m-CO2=0.05 y mNS=2)Linear (m-CO2=0.05 y mNS=2)mCO2=0.1 y mNS=2

Temperature (K)

Pre

ss

ure

(M

Pa

)

0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

f(x) = − 0.005993654 x² + 0.2028157487 x

f(x) = − 0.00893140549 x² + 0.248512405 x

f(x) = 0

313

Pressure (MPa)

%w

eigh

t CO

2

Solubility CO2 in a brine22% Na2SO4

EFFECT OF PRESSURE ON THE SOLUBILITY OF CO2 IN MGSO4

Dependence of the CO2 solubility in a 3% MgSO4 solution with pressure. This analysis have been done for different concentrations of sulfate

1000 1200 1400 1600

0.0

0.2

0.4

0.6

0.8

1.0

1300 1350 1400 1450 1500

0,0

0,1

0,2

60 bar 49 bar 40 bar 31 bar 22 bar 13 bar

Inte

nsity

(a.

u.)

Raman Shift (cm-1)

APPLICATION TO EUROPA

200 400 600 800 1000 1200 1400

-50

-45

-40

-35-30

-25

-20-15

-10

-50

m=0, T=273, CO2=3

m=0, T=298, CO2=3

m=1, T=273, CO2=3

m=1, T=313, CO2=3

m=1, T=323, CO2=3

m=1, T=353, CO2=3

m=2, T=273, CO2=3

m=2, T=313, CO2=3

m=2, T=333, CO2=3

m=2, T=353, CO2=3

m=1, T=273, CO2=5

m=1, T=273, CO2=5

m=1, T=273, CO2=10

Density of the cryomagma Na2SO4-CO2-H2O (Kg/m3)

0 5 10 15 20 25 301000

1100

1200

1300

MgSO4

Na2SO4

% weight

(/

3)r

kg

m

0.01

0.06

Pre

ssu

re (

MP

a)

Buoyancy of briny cryomagmas and style of the eruption

Cryomagmas charged in gas can suffer exolution if they depressurize to form a foam that has low density

APLICATION TO EUROPA

Following the terrestrial models, if volume% of gas is up to 75% of cryomagma, fragmentation would occur and the cryomagma could erupt violently to the surface

mNa2SO4 T d(m)0 273 0.430 298 0.461 273 0.471 313 0.551 323 0.571 353 0.622 273 0.522 313 0.62 333 0.632 353 0.67

Depth where the pressure for fragmentation can be reached in the crust of Europa

CONCLUSIONS

Cryomagmatic liquids have astrobiology interest

The evolution of cryomagmas from the interior of Europa may occur by several processes (final products, including biosignatures could be the exposed materials at the surface)

Simulation in laboratory may help to understand how these processes occur Clathration may be a style of differentiation in icy

satellites Exolution of gases in sulfate-rich aqueous

cryomagmas may derive in briny cryomagma buoyancy and explosive cryovolcanism