Habitability of a Large Ghost Crater in Chryse Planitia, Mars Dorothy Z. Oehler & Carlton C. Allen Astromaterials Research & Exploration Science Directorate (ARES) NASA - Johnson Space Center Chryse Houston, Texas , U.S.A. Planitia Viking 1 Mars Pathfinder Support from ARES and ARES Mission Enabling Grant MER Opportunity Oehler & Allen, Exploring Mars Habitability, June 14, 2011 HABITABILITY - GEOLOGIC CONTEXT HABITABILITY CRITERIA Acidalia Quasi Circular Planitia Long-Lived H20 Depressions • Run-off or upwelling sources (QCD’s) • Container (basin or lake) to trap Liquid H20 • Early Mars Chryse • Enhanced heat flow Regional (e.g. Tharsis) Planitia Hydrothermal vents Impact-related hydrothermal circulation - craters > 100 km (Newsom et al. 2001; Pope et al. 2000, 2006; Abramov & Kring 2005; Schwenzer et al. 2009; Ivanov & Outflows Pierazzo 2011) Renewing Nutrients • Run-off -- catchment • Upwelling (groundwater / hydrothermal) GEOLOGIC CONTEXT Oehler & Allen, Exploring Mars Habitability, June 14, 2011 GEOLOGIC CONTEXT: Drainage - Upwelling Catchment Estimated from valley networks (channels from Carr; USGS MarsGIS) Global Hydrology Noachian - E. Hesperian groundwater upwelling predicted in Chryse & Acidalia (Andrews-Hanna et al., 2007, 2011) Oehler & Allen, Exploring Mars Habitability, June 14, 2011 GEOLOGIC CONTEXT - Setting of Ghost Crater CRATER 120 km diameter; 34oN, 37oW Subdued (“ghost”/“stealth”) Noachian - Late Hesperian (~Early Hesperian) Legend mola_mud_volcanos OUTFLOW CHANNELS megt90n000eb.tif • Late Hesperian Value Elevation High> :- -18001800 m Low : -4850 Oehler & Allen, Exploring Mars Habitability, June 14, 2011 < - 4850 m mola_128deg_270e_hillshade.jp2 Value High : 210 Low : 115 mola_128deg_090e_hillshade.jp2 Value High : 255 Low : 0 GEOLOGIC CONTEXT - Setting of Ghost Crater MOUNDS > 18,000 mapped 60oN, 30oW 40,000 estimated Oehler & Allen, 2010., Icarus 208, 636-657. 30oN, 30oW Viking 1 500 km Mars Pathfinder Elevation > -1800 m Oehler & Allen, Exploring Mars Habitability, June 14, 2011 < - 4850 m Chryse-Acidalia Mounds: Mud Volcano Analog PSP_001916_2220 PSP_007770_2205 N 250 m 500 m PSP_008483_2250 MOC E21-00561 500 m PSP_008548_2205 P18_008021_2271 500 m 350 m 350 m 250 m 500 m P19_008483_2246 P17_007849_2255 500 m 500 m MOC S05-00934 PSP_008548_2205 PSP_008522_2210 500 m 500 m Oehler & Allen, Exploring Mars Habitability, June 14, 2011 Geologic Units Vastitas Borealis (Kreslavsky & Head, 2002; Tanaka et al., 2005) • Late Hesperian/ Early Amazonian - product of outflows • Polygons, mounds, ghost craters - modification • Outer margins constant elevation - groundwater table - or - emplacement in a standing body of water ACIDALIA Vastitas Borealis Interior Unit Vastitas Borealis Marginal Unit CHRYSE Oehler & Allen, Exploring Mars Habitability, June 14, 2011 FACIES Distal Fine-grained sediments; organic matter Legend mola_mud_volcanos megt90n000eb.tif Value Elevation > -1800 m Proximal High : -1800 Coarse-grained sediments Low : -4850< - 4850 m Oehler & Allen, Exploring Mars Habitability, June 14, 2011 mola_128deg_270e_hillshade.jp2 Value High : 210 Low : 115 mola_128deg_090e_hillshade.jp2 Value High : 255 Low : 0 GHOST CRATER RIM: Large knobs, irregularly shaped, lobate - possible hydrothermal circulation from impact INTERIOR: ~ 1000’s m fill with giant polygons & smaller, circular mounds 5 km Knobs at Rim Polygonal Fractures 50 km Mounds within Crater Fill P21_009353_2156 Oehler & Allen, Exploring Mars Habitability, June 14, 2011 P22_009498_2136 CRATER FILL GIANT POLYGONS: 1-10 km MOUNDS: • 0.25- 0.8 km diameter • pitted • central vents • circular • high albedo • moats • concentric form to crest • possible flow structures Similar to mounds in Acidalia. Mud volcano analog. 5 km Oehler & Allen, Exploring Mars Habitability, June 14, 2011 MOUNDS: Possible flow structures, concentric shape, younger than polygons P22_009498_2136 P22_009498_2136 1 km 1 km P22_009498_2136 P22_009498_2136 500 m 500 m Oehler & Allen, Exploring Mars Habitability, June 14, 2011 Mud Volcanism Mud volcanism creates microhabitats in the subsurface: • fracturing sediments • providing pathways for fluid migration Oehler & Allen, Exploring Mars Habitability, June 14, 2011 CONCLUSION - High Potential for Habitability WHY EXCEPTIONAL? Combination of LARGE SIZE and LOCATION (lowlands, outflows, distal facies) HIGH EXPLORATION POTENTIAL • Enhanced habitability • Potential to include organics • Potential of mud volcanoes to bring sediments from depth to the surface Oehler & Allen, Exploring Mars Habitability, June 14, 2011.