Water and Ice on Mars

Spring 2003

Water on Mars (Powerpoint Presentation)

WATER IN THE INNER SOLAR SYSTEM

Venus Too hot for liquid or ice; H20 deficient due to past runaway greenhouse

Moon/Mercury – Ice in vacuum environment (Dominated by evaporation rate and resupply)

Mars atmosphere sufficient to limit migration; C02 solid/vapor Equilibrium

Stability of Liquid Water on Surface on Mars

Phase diagram (1) 4 mb~3 mm Hg.

Triple point ~ 6 mb (why?) ; liquid unstable on surface

Very high Cl and S concentration and adsorption? Viking and Pathfinder evidence

No Liquid Water on Surface Now

Stability of Ice on Mars

North Residual cap- all ice in radiative balance with sun. South Residual cap not in radiative balance with sun but instead stabilized at CO2 solid/vapor temperature all summer by sublimating CO2. Why?

Leighton/Murray 1966 concept of separate CO2 and H2O equilibria.

H2O stability in subsurface in upper meters of temperate and equatorial areas depends on annual maximum annual temperature and frost point (198K), and on degree of atmospheric coupling.

Cryosphere concept of Clifford and others (1-3 kms in equatorial regions, with briney ground water beneath). Probability of ground water being breached in past in V. Marineris and in northern hemisphere. S to N transfer of water on surface and subsurface.

Paige 1992 analysis suggesting ice could be stable within few meters of surface everywhere that high albedo and low thermal inertia were present.

Variations Over Time

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Obliquity global pressure temp variations on scale of 10*5 to 10*6 years. Chaotic obliquity likelihood. Thermal wave to 100 – 1000 meters

Transition from early dense atmosphere – early ice cover? Early open water bodies? (Malin and Edgett, Science , 2000 image analysis). Connected with LHB?

Ice covered lakes like Antarctica today.

Morphological Evidence of Crustal Ice and Past Surface Water and Ice

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Fluidized ejection blankets on many, but not all, Martian craters

Thermokarst? Chaotic terrain suggestive of collapse due to removal of ground ice.

Patterned ground; analogous to ice rich soils in Arctic, but at much larger scales. 100 - 300 m scale? 2-20 km also on Mars!

Terrain softening in mid latitude areas

Ophar landslide seems to have transitioned to debris flow and then ponded runoff in V. Marineris (under ice?)

Doughnut-shaped ridges, due (?) to melting/sublimation of ice blocks from glaciation.

http://marsweb.jpl.nasa.gov/mgs/msss/camera/images/

References

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