Broad Perspectives on Preferred Types of Mars Science Laboratory Landing Sites:

1. Broad Perspectives on Preferred Types of Mars Science Laboratory Landing Sites: Experience from Characteristics of Previous Landing Sites and Developing Sedimentologic Facies Models M. Golombek and J. Grotzinger Jet Propulsion Laboratory and Caltech

2. Golombek & Grotzinger’sGuide to MSL Landing Sites • Layered Sedimentary Rocks • Extensive Section • Outcrop, No Float • Not Hesperian or More Cratered Surface • No/Little Dust • Dark, Low Albedo • Low Energy Depositional Sedimentary Facies • Clay rich mudstones distal fluvio-deltaic or lacustrine • Bottom-growth evaporites - sulfates

3. MSL Science Objectives • Focus on Habitable Environment • PP Requirements Focus on Ancient Habitable Environments • Layered Sedimentary Rocks • Well Suited to Address Ancient Environments • Meridiani Planum Sulfates • Top of Section of Layered Sedimentary Rocks • Formed in Late Noachian • Approximately Coeval w/Geomorphic Indicators • Valley Networks, Eroded Terrain, Layered Rocks • Formed in Wet, Likely Warm Environment

4. Landing Sites on Mars 5 “Ground Truth” Samples VL2 VL1 MPF 15°N Meridiani 15°S Gusev Meridiani Eroded Highlands

5. Smooth Plains Overly Noachian Cratered Terrain Generally Bury Valley Networks flow to NW, Down Topographic Slope Created by Tharsis Loading Population Old Degraded Craters >1 km Diameter are Noachian Lightly Cratered Indicates Young Surface Age Meridiani Planum Site

6. Bright Unit Mapped As Package of LN Sedimentary Rocks Surface Age Late Amazonian Hesperian Craters Gone Erosion of 10-80 m of Material Meridiani Hynek, 2004

7. Meridiani Planum Late Noachian Denudation ~1 km Erosion in LN [Just before Evaporites Deposited] Argued for Precipitation & Runoff Warm and Wet Environment Hynek and Phillips [2001]

8. Meridiani Planum Late Noachian Sulfates “Dirty Evaporites” Liquid Water Stable Wet and Likely Warm Environment

9. Dells MI Mosaic Dirty Evaporites Document Early Wet & Likely Warm Environment

10. Overgaard

11. Burns Formation Upper unit Lower unit Middle unit

12. Network of Interdune Depressions

13. Interdune Depression

14. 100 km

15. MSL to Layered Sedimentary Rocks Likely Formed in Wet and Warm Conditions and Record Aqueous Environment OMEGA Identified Sulfates in Many Such Terrains Substantial Stratigraphic Section Accessible [Meridiani ~10 m]

16. No Float! Outcrops OnlyInstructions on Door of JPL 183-803, 1998 to presentOccupant: T. Parker

17. No Float/OutcropGusev Hesperian Cratered Plains Gusev Random Sample Hesperian Cratered Plains Variable Thickness Impact Generated Regolith Likely Formed as Lava Flows No Outcrop Found Cratered Plains

18. Cratered PlainsAngular Basalt FragmentsLikely Basalt FlowsImpact Generated Regolith

19. Bonneville Fresh Crater, Fresh Ejecta, Little evidence for Backwasting No Debris Chutes or Talus, Jumbled Regolith of Basalt Ejecta ~10 m Thick No Outcrop

20. Viking Lander 1 Late Hesperian Cratered Surface Limited Low Outcrop Lot of Rock Float

21. Viking Lander 2 No Outcrop Rocks are Float

22. Lightly Cratered Surface for Intact Stratigraphy Cratered Surface: Beware of Float, Regolith and No/Little Outcrop

23. No Dust, Dark Low-Albedo Site Meridiani - First Landing Site in Dark Region, Albedo Low ~0.1 Basalt Sand, Hematite Granule Lag Surface Ripples No/Little Dust to Mask Remote Sensing; More Effective Surface Operations to ID Rocks & Soils to Investigate Further

24. Sedimentary Facies • Low Energy Environments • Maximize Accumulation & Preservation of Biomarkers • Burns Formation at Meridiani • Most High Energy Sand Dune and Sand Sheet • Not Optimal for Accumulation or Preservation • Two Optimal Facies • Clay Rich Mudstones: Deposited in Distal Fluvio-deltaic or Lacustrine Setting • Bottom Growth Evaporites • Examples of Each & How to Recognize • Ideal Landing Site Has Both Facies

25. Interdune Eolian Dune Sand Sheet

26. Sulfate (Gypsum) Evaporites in Playa Lake

27. Microbial Mats Being Entombed, Could Protect from Degradation (Salts Impermeable) Chemical sediments have high potential to preserve organic compounds

28. Microbial Mat Textures Preserved in Evaporites

29. Juventae Chasma Example of Layered Sulfates Headwaters of Maja Valles Floor Around -2 km Elevation 4.5°S, 297.5°E

30. 4S 297E 5S 296.5E

31. Juventae Chasma Layered Deposits Gypsum (Ca Sulfate) Kieserite Mg Sulfate) Stratigraphic Transition - Minerals with Different Solubilities Bibring et al. 2005

32. Land and Traverse on Sand Sheet Sample Stratigraphic Column

33. Example Distal Clay Rich Site Clinoforms On Earth, organic material preferentially sequestered by clay minerals Preservation organics enhanced by phyllosilicate surfaces Search Strategy - Look for phyllosilicates in spectral imaging and Stratal Geometries to Identify Distal Environments - Clays and Organics 200 m

34. Clinoforms Prograding Delta Clinoforms Channel

35. Prograding Clinoforms Condensed Section, Decrease in Grain Size, Distal Clay Rich Enhanced Organic Accumulation and Preservation

36. Prograding Clinoforms Yellow Lines Define Single Depositional Sequence Convergence of Clinoforms - Section Condensation Decrease in Grain Size Accumulation of Clay Minerals and Organics

37. Depositional Sequences • Conformable succession of genetically-related strata, bounded at the top and base by: • Unconformities (surfaces of erosion) or their • Correlative conformities (surfaces lacking erosion)

38. Sequence Stratigraphy Seismic Reflection Data - Prograding Clinoforms Sequence Boundaries - Stratal Truncations and Onlap Define Cinoforma Interpretation of Facies - Brown Shales, Downdip of Sands

39. Permian Clinoforms in Last Chance Canyon

40. Permian Clinoforms in Last Chance Canyon

41. Golombek & Grotzinger’sGuide to MSL Landing Sites • Layered Sedimentary Rocks • Extensive Section, Intact Stratigraphy, Known Geologic Setting - Related to Geology of Mars • Outcrop, No Float, Lightly Cratered • Not Hesperian or More Cratered Surface • No/Little Dust, Effective Surface Remote Sensing • Dark, Low Albedo • Low Energy Depositional Sedimentary Facies • Clay rich mudstones distal fluvio-deltaic or lacustrine setting, Look for clays and clinoforms • Bottom-growth evaporites - sulfates, extensive stratigraphic section, better chance to find bottom growth