Experimental Methods Solutions were prepared of 10, 15, 20, 25 wt% MgSO 4 ; and 10.9, 13.7, 17.8,...
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Transcript of Experimental Methods Solutions were prepared of 10, 15, 20, 25 wt% MgSO 4 ; and 10.9, 13.7, 17.8,...
Experimental MethodsExperimental Methods
Solutions were prepared of 10, 15, 20, 25 wt% MgSO4; and 10.9, 13.7, 17.8, and 18.0 wt% FeSO4
Experimental conditions inside Andromeda Chamber (Figure 2):
Atmosphere temperature ranging from -5°C to 0°C
7 mbar CO2 atmosphere
Relative Humidity (less
than) 2%
Evaporation rates determined
(in mm hr-1) from mass loss
slopes
Characteristics of Mg2+/Fe2+ Sulfate Brines Under Martian Conditions
C. Nicholson, V. Chevrier, T. [email protected], [email protected]
W.M. Keck Laboratory for Space Simulation, Arkansas Center for Space and Planetary Sciences, University of Arkansas, Fayetteville, Arkansas 72701
IntroductionIntroduction
MgSO4
Specific Locals: Meridiani Planum, Valles Marineris, Margaritifer Sinus, and Terra Meridiani1
Involved in Martian History: Currently found on Mars in large deposits (~5% of Martian soils)1
Suggests liquid source of water
FeSO4
Specific Locals: Meridiani Planum, Gusev Crater3
Involved in Martian History:- Also currently found on Mars
Good comparison to Magnesium because it is also a 2+ ion and makes 7 hydrate
Evaporation rates are used to determine water stability duration
ConclusionsConclusions
Evaporation rates are much lower than expected => Increased liquid brine stability at lower temperatures
Due to crystallization of hydrates: i.e. MgSO4·7H2O, …Longer residence time of liquid water on Mars
DataData
ResultsResults
Sulfate samples experiences mass loss when exposed to
~7 mbar of CO2
Determined evaporation rates of MgSO4 (Fig. 4) & FeSO4 (Fig.
5) brine solutions at the corresponding surface sample
temperature Both demonstrate an effect of sample concentration on the
resulting evaporation rates Formation of an ice cap slows sublimation process
Figure 2: Andromeda Chamber
Figure 3: Relative Mass Loss versus Time of
various brine samples
Figure 4: Evaporation Rate versus Temperature of MgSO4 brine samples; includes calculated evaporation lines of Water Ice, Liquid Water and 25 wt% MgSO4
Figure 5: Evaporation Rate versus Temperature of FeSO4
brine samples
AcknowledgementsAcknowledgements
Thank you Katie Bryson for her continuous input and contagious enthusiasm, and Walter Graupner for his technical support.
ReferencesReferences[1] Gendrin, Aline, et al. (2005) Science 307, p. 1587-1591.
[2] Bibring, J.P., et al. (2007) Science 317, p. 1206-1210.
[3] Lane, Melissa D., et al. (2004) Geophysical Research Letters 31.
Figure 8: Burn’s Cliff in Meridiani Planum; large magnesium sulfate deposit in the sediment layering
Figure 1: Brine deposit at West Candor Chasma; lighter colored sediment is kieserite (MgSO4·1H2O), darker sediment is iron oxides.
Figure 6: Theoretical Evaporation Rates of Crystallizing MgSO4 & FeSO4 hydrated phases; includes theoretical saturated FeSO4 (18 wt%) & MgSO4 (26 wt%)
Figure 7A: FeSO4 brine at pressure and temperature
near the beginning of chamber run;
Figure 7B: FeSO4 brine after completion of chamber
run, also at pressure and temperature
A B
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
268.00 269.00 270.00 271.00 272.00 273.00
Temperation (K)
Eva
po
rati
on
Rat
e (m
m h
r-1
)
18.0 wt%
13.7 wt%
10.9 wt%
17.8 wt%
Liquid Water
Water Ice
Vac.Sys
Coolant
Insulation
Hygrometer
Platform
Hoist
Lid
Cooling coils
Sampling ports
Thermocouples
Balance
Dry Ice
Thermocouple 1 m