Aqueous Sedimentary Depositional Environments, Meridiani Planum, Mars

Transcription

1 Aqueous Sedimentary Depositional Environments, Meridiani Planum, Mars John Grotzinger on behalf of MER Athena Science Team

2

3 The Team

4 The PI

5 The Rovers Remote Sensing Package Pancam Mast Assembly (PMA) Pancam Mini-TES In-Situ Package Instrument Deployment Device (IDD) Microscopic Imager Alpha Particle X-Ray Spectrometer Mössbauer Spectrometer Rock Abrasion Tool

6 Opportunity at Meridiani Planum Meridiani Gusev

7 Hematite: Mineralogic Beacon

8 Meridiani Landing Site

9 Spirit: View from Lander 5 metres Opportunity: View from Lander 5 metres

10 Geological Traverse

11 Geological Map

12 El Capitan

13

14 Bromine vs. Chlorine

15 APXS Results: High S in Rocks 40 Fe 2 O35 3 (wt.%) HEMATITE-RICH Spherulerich Soil Dust Spherule-rich Fract fill/vein Basalts Soil Bright Soil Soil on Rock Nat Rk surface Rk w/soil Rk nat surf Rk RAT'd Basalt END MEMBERS (SCHEMATIC) RAT'd Rocks SULFATES SO 3 (wt.%, total S as SO 3 ) B. Jolliff

16 APXS Results: Crud Extraction 12 Al 2 O 3 (wt.%) Spherulerich Soil Soil Bright Soil Soil on Rock Nat Rk surfa ce RAT'd Rocks Soil Dust Spherule-rich Fract fill/vein Rk w/soil Rk nat surf Rk RAT'd Basalt If subtract 60% of dust or basalt component from average RAT d rock composition, Al 2 O 3 and Cr 2 O 3 go to zero at ~50% SO SO 3 (wt.%, total S as SO 3 ) B. Jolliff

17 N. Tosca

18 Rio Tinto, Spain

19 Mini-TES: Hematite Distribution

20 Soil Granules (Spherules)

21 Pancam on Stone Mountain

22 Microimager: Spherules in Outcrop

23 Concretions

24 Spherules Not Concentrated Along Bedding

25 Distribution of Concretions

26 W. Watters, D. Fike

27 Doublets Triplet

28 The Berry Bowl

29 Mössbauer on the Berry Bowl

30 N. Tosca

31 Concretions: Two Types?

32

33 Vugs

34 Sulfate Minerals: Gypsum?

35 Evaporite-Filled Crystal Molds on Earth

36 The Rocks are Sandstones Laminae Defined by Variable Grain Size 0.3 mm Medium Grain size Well Rounded 0.8 mm

37 Bedforms in Flowing Water Southard and Bouchwal, 1990

38 Current Ripples in Water 6 hours of ripple migration Image is 60x40 cm Flume experiments by Dave Rubin and Jon Nelson, USGS

39 Current Ripples in Cross Section Simulation by Dave Rubin, USGS

40 Ripple Cross-Bedding on Mars

41 Ripple Cross-Bedding

42 Festoon Cross-Bedding on Earth

43 Modern Mars Analog: Umm a Samin Braid Plain Modern Playa Dunes 100 km

44 Network of Interdune Depressions

45 Interdune Depression

46 Modern Interdune Depression: Namib Desert

47

48 Endurance Chemostratigraphy

49 A Trail of 11 RAT Holes

50 Ratio to surface rock average Depth in crater A. Haldemann

51 Changes Down Section: Texture Ontario Diamond Jenness

52 Diagenetic Model S. McLennan, N. Tosca

53 S. McLennan, N. Tosca

54 S. McLennan, N. Tosca

55 Other Evidence for Liquid Water on Mars Modern Ancient

56 What about (astro)biology? Rover reveals Mars was once wet enough for life (MsNBC) Red planet may have been hospitable to life (CNN) Mars could once support life, scientists now say, but did it? (NY Times)

57 Meridiani environment appears to have been acidic, hypersaline, and only intermittently wet. Life exists at such extremes on Earth. But Meridiani data suggest potential challenges to origin as well as persistence of life. Rio Tinto Extremophiles

58 Could Life Begin in Acidic Waters? Several key reactions do not proceed at acidic ph: e.g. Strecker synthesis (generates amino acids) Proteins and DNA both readily hydrolyzed in acidic waters Experimental growth of nucleotides yields triple helix in acidic waters The oxidizing surface of Mars would make things worse. We need to understand when Meridiani-like conditions were established on Mars. Was there ever a surface environment that was more conducive to prebiotic chemistry?

59 The Good News Evidence of any life that might have existed might well be preserved in chemical sediments and concretions. Chemical and textural details of Meridiani salts and iron oxides likely to reveal much about environmental history. All this favors Meridiani Planum as a target for sample return.