Evidence of Glaciers on Mars TJ Schepker G565 Glacial GeomorphologySpring 2009 Hubblesite.org

Overview TJ Schepker G565 Glacial GeomorphologySpring 2009 A.Background on Mars B.Polar Ice on Mars Fingerprint terrain Polar dunes Layered deposits C.Model for rock glacier formation Hellas region Glacier tongue D.Impact Craters “Normal” crater ice Rock glaciers in craters E.Mountain/piedmont glaciers Model Morphological support Analysis of Olympus Mons F.Ground Ice? G.Conclusions

Background TJ Schepker G565 Glacial GeomorphologySpring 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

The Obvious place to look? The Poles! TJ Schepker G565 Glacial GeomorphologySpring 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

“Fingerprint” Terrain TJ Schepker G565 Glacial GeomorphologySpring 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

Polar Dune Terrain TJ Schepker G565 Glacial GeomorphologySpring 2009 HIRISE/NASA Evidence of geyser activity?

Layered Deposits TJ Schepker G565 Glacial GeomorphologySpring 2009 Alternating layers of ice and dust/rock Potentially will give us climatic record Mars Express/ESA, HIRISE/NASA

TJ Schepker G565 Glacial GeomorphologySpring 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

Example of the Model? Hellas Region TJ Schepker G565 Glacial GeomorphologySpring 2009 MRO/NASA

Glacial “Tongue” - Hellas Region TJ Schepker G565 Glacial GeomorphologySpring 2009 Eskers Very different morphology than most Thought to represent a “wet” galcier Both-HIRISE/NASA

Where Else To Look? Impact Craters… TJ Schepker G565 Glacial GeomorphologySpring 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

Crater Based Rock Glacier TJ Schepker G565 Glacial GeomorphologySpring 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

Another Target For Ice? Mountains! TJ Schepker G565 Glacial GeomorphologySpring 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 mi 2

Model of Glacial Formation and Evolution: Olympus Mons TJ Schepker G565 Glacial GeomorphologySpring 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

Different Morphologies on Mars TJ Schepker G565 Glacial GeomorphologySpring 2009 A) Ganges Chasma, Valles Marineris radial grooved texture of debris apron B) Daedalia Planum blocky texture of flow surface with many tongues and toes C) Olympus Mons scarp sub parallel arcuate ridges in the debris apron Milkovich et al., 2005

Olympus Mons Geomorphology TJ Schepker G565 Glacial GeomorphologySpring 2009 Milkovich et al., 2005

Ground Ice? TJ Schepker G565 Glacial GeomorphologySpring 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

Conclusions TJ Schepker G565 Glacial GeomorphologySpring 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

References TJ Schepker G565 Glacial GeomorphologySpring 2009 ESA: Mars Express. European Space Agency.. Head J.W. et al., Tropical to mid-latitude snow and ice accumulation, flow and glaciation on Mars. Nature, 434: March 17, HIRISE: High Resolution Imaging experiment. Department of Planetary Sciences, Lunar and Planetary Institute, The University of Arizona.. Milkovich, S.M. et al., 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.. The Hubble Telescope. NASA.. Questions? HIRISE/NASA