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CH 4 @sI (Fortes '12): d(mean)=0.962 g/mL High Pressure Phases of Gas Clathrate Hydrates and their Impact to the Habitability of the Icy Moons F. Izquierdo-Ruiz 1 ,2 , A.S.J. Méndez 1 , J.M. Recio 2 , O. Prieto-Ballesteros 1 . e-mail: [email protected] 1) Centro de Astrobiología, INTA-CSIC, Madrid, 28850, Spain 2) Dept. Química Física y Analítica, U.Oviedo, Oviedo, 33006, Spain Introduction Clathrate hydrates are proposed as constituents of the icy crusts and water rich reservoirs in the moons of the giant planets of the Solar System, e.g. as the source of CH 4 in Titan’s atmosphere, or in Enceladus as the origin of the geyser compounds. Remote measurements show CO 2 presence on the surfaces of giant moons of Jupiter, though it is unclear whether it is in the interior and interacts with water. In Ganymede, aqueous layers are suggested to be deep within the moon, between layers of different water ice phases. Geophysical models show that the pressure in the ocean is up to 1.3 GPa, so we need to understand the interactions between H 2 O and CO 2 under these conditions in order to constraint the carbon state in the aqueous layers. One way of interaction is forming clathrate hydrates. . From Pressures and Cavities to Densities Efect of high pressure phases on the giant icy moons Ganymede. Credit: NASA Small 5 12 sI Large sII Large sH Medium sH Large FIS (Filled Ice Structure) 6 2 5 12 6 3 5 12 6 3 5 6 4 3 6 8 5 12 Channels nCages per cell sI 2 sII 16 sH 3 6 Cages per cell 8 Cages per cell 1 Cage with 3 CH 4 2 Cages per cell Host:Guest 2H 2 O:1Guest Type Symm sI sII sH FIS Pm3m Fd3m P6/mmm Imcm 46 136 34 8 nH 2 O cell Press. Range (GPa) 0—0.9 (CH 4 ) 0—0.7 (CO 2 ) 0—0.5 (CH 4 ) metastable 0.9—1.6 (CH 4 ) 1.6—42* (CH 4 ) 0.7—1.0 (CO 2 )** * Max pressure studied but not decomposed ** Approximate values due to recent discovery High density of CO 2 clathrates might support a multilayered structure. However, it is not clear if high pressure clathrates can form at depth from its separate components. It is known that they can be transformed from low pressure phases in solid-solid phase transitions. Laboratory experiments are running to shed light on the former process. The sI to FIS transition require a convective behavior of the icy layer in order to sink the sI phase to deeper levels. If it occurs, this transition is associated with a remarkable change in volume and other thermo- dynamical parameters. Molecules containing essential elements for life, which would be released during early differentiation of the satellite, could have been retained at upper clathrate layers. Clathrate components would react in aqueous layers if they dissociate during further heating episodes. Future JUICE mission will help to understand the structure and habitability of Ganymede. Guest Phase P(GPa) T(K) d(g/mL) CH 4 sH 0.86—2.26 Room Temp. 1.018—1.083 FIS 2.17—42.0 Room Temp. 1.117—1.962 CO 2 sI –– 77-240 1.119-1.154 FIS –– 173 1.825 CO 2 @FIS CO 2 @FIS CO 2 @sI CO 2 @sI Ganymede models (after Sohl et al. 2002, Vance & Brown 2013, Vance et al. 2014) Arrows show the clathrate gravitational stable position Titan geophysical models (after Fortes 2012) Arrows indicate gravitational stable position of clathrates CH 4 @sI CH 4 @sH References Phase diagram of water ice (dotted line) and CO 2 clathrate (solid thick line), where thermal profiles of Ganymede are shown (modified from Sohl et al. 2010, Bollengier et al. 2013). Low pressure phase diagram of CO 2 -clathrate sI is in the inset. Buffett B.A. (2000) Ann. Rev. Earth Plan. Sci., 28:477. Dalton J.B. (2010) Space Sci. Rev. 153:219. Waite Jr. J.H. et al. (2009) Nature 460:487 Niemann H.B. et al. (2010) J. Geophys. Res. 115:E12006 Mousis O. et al. (2006) Astron. Astrophys. 448: 771 Fortes A.D. et al. (2010) Space Sci. Rev. 153:185 Vance S. et al. (2014) Plan. And Space Sci. 96:62. Fortes A.D. (2012) Plan. And Space Sci. 60:10 Bollengier O. et al. (2013) Geochim. Cosmochim. Acta 119:322. Vance S. and Brown M. (2013) Geochim. Cosmochim. Acta 110:176 Sohl F. et al. (2002) Icarus 157: 104 Sohl F. et al. (2010) Space Sci. rev. 153:485 Bland M.T. et al. (2009) Icarus 200:207. Loveday J.S. et al. (2008) PCCP 10:937. Hirai H. et al. (2010) J. Chem. Phys. 133:124511 Takeya S. et al. (2010) JACS 132:524 Tulk C.A. et al (2014) J. Chem. Phys. 141:174503. Temperature (K) 320 300 280 240 260 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 340 1.8 Ih VI V II III Liquid water CO2-SI CO2-HP 0.00 2.00 4.00 6.00 8.00 10.00 240 260 280 300 Q1 Q2 Liquid water CO2-SI Ih FIS CO L D PROF I L E WARM P ROFILE Pressure (GPa) x10 -3
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CH4@sI (Fortes '12): d(mean)=0.962 g/mL
High Pressure Phases of Gas ClathrateHydrates and their Impact to the Habitability of the Icy Moons
F. Izquierdo-Ruiz1,2, A.S.J. Méndez1, J.M. Recio2, O. Prieto-Ballesteros1. e-mail: [email protected]) Centro de Astrobiología, INTA-CSIC, Madrid, 28850, Spain
2) Dept. Química Física y Analítica, U.Oviedo, Oviedo, 33006, Spain
IntroductionClathrate hydrates are proposed as constituents of the icy crusts and water rich reservoirs in the moons of the giant planets of the Solar System, e.g. as the source of CH4 in Titan’s atmosphere, or in Enceladus as the origin of the geyser compounds. Remote measurements show CO2 presence on the surfaces of giant moons of Jupiter, though it is unclear whether it is in the interior and interacts with water. In Ganymede, aqueous layers are suggested to be deep within the moon, between layers of different water ice phases. Geophysical models show that the pressure in the ocean is up to 1.3 GPa, so we need to understand the interactions between H2O and CO2 under these conditions in order to constraint the carbon state in the aqueous layers. One way of interaction is forming clathrate hydrates..
From Pressures and Cavities to Densities
Efect of high pressure phases on the giant icy moons
Ganymede. Credit: NASA
Small
512
sI Large sII Large
sH Medium sH Large FIS (Filled Ice Structure)
62512 63512
635643 68512
Channels
nCagesper cellsI 2
sII 16
sH 3
6 Cages per cell 8 Cages per cell
1 Cage with 3 CH4 2 Cages per cell
Host:Guest2H2O:1Guest
Type Symm
sI
sII
sH
FIS
Pm3m
Fd3m
P6/mmm
Imcm
46
136
34
8
nH2Ocell
Press. Range(GPa)
0—0.9 (CH4)0—0.7 (CO2)
0—0.5 (CH4)metastable
0.9—1.6 (CH4)
1.6—42* (CH4)0.7—1.0 (CO2)**
* Max pressure studied but not decomposed** Approximate values due to recent discovery
High density of CO2 clathrates might support a multilayered structure. However, it is not clear if high pressure clathrates can form at depth from its separate components. It is known that they can be transformed from low pressure phases in solid-solid phase transitions. Laboratory experiments are running to shed light on the former process.
The sI to FIS transition require a convective behavior of the icy layer in order to sink the sI phase to deeper levels. If it occurs, this transition is associated with a remarkable change in volume and other thermo-dynamical parameters.
Molecules containing essential elements for life, which would be released during early differentiation of the satellite, could have been retained at upper clathrate layers. Clathrate components would react in aqueous layers if they dissociate during further heating episodes.
Future JUICE mission will help to understand the structure and habitability of Ganymede.
Guest Phase P(GPa) T(K) d(g/mL)
CH4
sH 0.86—2.26 Room Temp. 1.018—1.083
FIS 2.17—42.0 Room Temp. 1.117—1.962
CO2
sI –– 77-240 1.119-1.154
FIS –– 173 1.825
CO2@FISCO2@FIS
CO2@sICO2@sI
Ganymede models (after Sohl et al. 2002, Vance & Brown 2013, Vance et al. 2014)Arrows show the clathrate gravitational stable position
Titan geophysical models (after Fortes 2012)Arrows indicate gravitational stable position of clathrates
CH4@sI
CH4@sH
References
Phase diagram of water ice (dotted line) and CO2 clathrate (solid thick line), where thermal profiles of Ganymede are shown (modified from Sohl et al. 2010, Bollengier et al. 2013). Low pressure phase diagram of CO2-clathrate sI is in the inset.
Buffett B.A. (2000) Ann. Rev. Earth Plan. Sci., 28:477. Dalton J.B. (2010) Space Sci. Rev. 153:219.Waite Jr. J.H. et al. (2009) Nature 460:487 Niemann H.B. et al. (2010) J. Geophys. Res. 115:E12006 Mousis O. et al. (2006) Astron. Astrophys. 448: 771
Fortes A.D. et al. (2010) Space Sci. Rev. 153:185 Vance S. et al. (2014) Plan. And Space Sci. 96:62.Fortes A.D. (2012) Plan. And Space Sci. 60:10Bollengier O. et al. (2013) Geochim. Cosmochim. Acta 119:322. Vance S. and Brown M. (2013) Geochim. Cosmochim. Acta 110:176Sohl F. et al. (2002) Icarus 157: 104 Sohl F. et al. (2010) Space Sci. rev. 153:485
Bland M.T. et al. (2009) Icarus 200:207. Loveday J.S. et al. (2008) PCCP 10:937. Hirai H. et al. (2010) J. Chem. Phys. 133:124511Takeya S. et al. (2010) JACS 132:524 Tulk C.A. et al (2014) J. Chem. Phys. 141:174503.
Temperature (K)
Pre
ssu
re (
MP
a)
320300280240 260
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
340
1.8
Ih
VI
V
IIIII Liquid waterCO2-SI
CO2-HP
0.00
2.00
4.00
6.00
8.00
10.00240 260 280 300
Q1
Q2
Liquidwater
CO2-SIIh
FIS
CO
LD
PR
OF
ILE
WA
RM
PR
OFILE
Pre
ssur
e (
GP
a)
x10-3
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