Download - Evidence of Glaciers on Mars TJ Schepker G565 Glacial GeomorphologySpring 2009 Hubblesite.org
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Evidence of Glaciers on Mars
TJ Schepker G565 Glacial Geomorphology Spring 2009
Hubblesite.org
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Overview
TJ Schepker G565 Glacial Geomorphology Spring 2009
A. Background on Mars
B. Polar Ice on MarsFingerprint terrainPolar dunesLayered deposits
C. Model for rock glacier formationHellas region Glacier tongue
D. Impact Craters“Normal” crater iceRock glaciers in craters
E. Mountain/piedmont glaciersModelMorphological supportAnalysis of Olympus Mons
F. Ground Ice?
G. Conclusions
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Background
TJ Schepker G565 Glacial Geomorphology Spring 2009
Mars compared to earth:
•Smaller•Thinner atmosphere•Lower gravity•Less sunlight = colder•2 compositions of Ice: Water Ice and Carbon Dioxide Ice
Obliquity, eccentricity (ellipsoid) combine to allow ice and glacial formation on Mars
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The Obvious place to look? The Poles!
TJ Schepker G565 Glacial Geomorphology Spring 2009
Mars Express/ESA, HIRISE/NASA
Poles show seasonal variation:
•Winter = Expansion of Ice “sheets”
•Condensation of Carbon Dioxide Ice at temperatures as low as -150 °C
•Summer = Evaporation of carbon dioxide ice
•only water ice remains
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“Fingerprint” Terrain
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Only poles show uncovered ice in significant quantities
•Spiral, lobate pattern common in polar ice
• Fingerprint “texture” formed via wind and Aeolian processes
HIRISE/NASA
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Polar Dune Terrain
TJ Schepker G565 Glacial Geomorphology Spring 2009
HIRISE/NASA
•Evidence of geyser activity?
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Layered Deposits
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Alternating layers of ice and dust/rock
•Potentially will give us climatic record
Mars Express/ESA, HIRISE/NASA
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TJ Schepker G565 Glacial Geomorphology Spring 2009
Model of Glacial Formation and Evolution:Rock Glaciers
•No Ice at surface except at or near poles
•Ice originates from below the surface and “ponds”
•Sublimation of uncovered ice under present conditions makes it extremely difficult to see glacier evolution
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Example of the Model? Hellas Region
TJ Schepker G565 Glacial Geomorphology Spring 2009
MRO/NASA
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Glacial “Tongue” - Hellas Region
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Eskers
•Very different morphology than most
•Thought to represent a “wet” galcierBoth-HIRISE/NASA
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Where Else To Look? Impact Craters…
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Provide shelter for ice against sun exposure
•Ice must be transported from poles due to seasonal shifts in atmospheric conditions
•Impacts can also release liquid water or provide a pathway for its escape from below
Mars Express/ESA, HIRISE/NASA
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Crater Based Rock Glacier
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Like the debris fan around Hellas, many thought this was a fluvial sediment accumulation
•Mars Reconnaissance Orbiter (MRO) demonstrated the presence of ice just below the surface
MRO/NASA
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Another Target For Ice? Mountains!
TJ Schepker G565 Glacial Geomorphology Spring 2009
Milkovich et al., 2005
Olympus Mons:
•Most massive volcano in the solar system
•Surrounded by large cliffs but has shallow slopes
•~86,600 ft above MSL of Mars (~3x as high as Everest)
•~342 miles wide
•Caldera: ~1960 mi2
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Model of Glacial Formation and Evolution:Olympus Mons
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Much closer to equator
•Ice flows down slope on Olympus Mons
•Exposed Ice will sublimate at lower elevation
•Mass wasting and effective debris coverage important to survival
Milkovich et al., 2005
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Different Morphologies on Mars
TJ Schepker G565 Glacial Geomorphology Spring 2009
A) Ganges Chasma, Valles Marineris
radial grooved texture ofdebris apron
B) Daedalia Planumblocky texture of flow
surface with many tongues and toes
C) Olympus Mons scarp sub parallel arcuate ridges
in the debris apronMilkovich et al., 2005
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Olympus Mons Geomorphology
TJ Schepker G565 Glacial Geomorphology Spring 2009
Milkovich et al., 2005
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Ground Ice?
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Network of polygonal cracks and elongated, scallop-shaped depressions
•Similar to thermal contraction cracks in periglacial and alpine regions
•Steep pole/gentle equator facing slopes
HIRISE/NASA
Western Utopia Planitia, northern lowlands
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Conclusions
TJ Schepker G565 Glacial Geomorphology Spring 2009
•Glacial environments do and have existed on Mars for a long time
•Ice is found in both polar and non-polar regions, but much of the geomorphology on Mars is poorly understood
•A diverse set of terrains and morphologies exist suggesting complex and diverse micro-climatic conditions on Mars
•Layered polar deposits should give a detailed climatic record similar to that obtained from Antarctic ice cores
•Most ice on Mars (non-polar) originates from below the surface and depends on rock and sediment coverage to avoid sublimation
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References
TJ Schepker G565 Glacial Geomorphology Spring 2009
ESA: Mars Express. European Space Agency. <http://www.esa.int/SPECIALS/Mars_Express/>.
Head J.W. et al., 2005. Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars. Nature, 434: March 17, 346-351
HIRISE: High Resolution Imaging experiment. Department of Planetary Sciences, Lunar and Planetary Institute, The University of Arizona. <http://hirise.lpl.arizona.edu/>.
Milkovich, S.M. et al., 2005. Debris-Covered Piedmont Glaciers Along The Northwest Flank Of The Olympus Mons Scarp: Evidence For Low-Latitude Ice Accumulation During The Late Amazonian Of Mars. M.S. Thesis, Brown University.
NASA , website. <http://www.nasa.gov>.
The Hubble Telescope. NASA. <http://www.hubblesite.org>.
Questions?
HIRISE/NASAHIRISE/NASA