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

Experience from Characteristics ofPrevious Landing Sites and Developing

Sedimentologic Facies Models

M. Golombek and J. GrotzingerJet Propulsion Laboratory and Caltech

Golombek & Grotzinger’s Guide 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

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

VL1 MPF

Meridiani

VL2

Gusev

Landing Sites on Mars5 “Ground Truth” Samples

15°N

15°S

Meridiani Eroded Highlands

Meridiani Planum Site

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

Bright Unit Mapped As Package of LN Sedimentary RocksSurface Age Late AmazonianHesperian Craters GoneErosion of 10-80 m of Material

Meridiani

Hynek, 2004

Meridiani Planum Late Noachian Denudation

Hynek and Phillips [2001]

~1 kmErosionin LN[Just beforeEvaporites Deposited]

Argued forPrecipitation& Runoff

Warm and WetEnvironment

MeridianiPlanum

Late NoachianSulfates“Dirty Evaporites”

Liquid WaterStable

Wet andLikely WarmEnvironment

Dells MI Mosaic

Dirty Evaporites Document Early Wet & Likely Warm Environment

Overgaard

Lowerunit Middle unit

Upperunit

BurnsFormation

Network of Interdune Depressions

Interdune Depression

100 km

MSL to Layered Sedimentary Rocks

Likely Formed in Wet and Warm Conditions and Record Aqueous EnvironmentOMEGA Identified Sulfates in Many Such TerrainsSubstantial Stratigraphic Section Accessible [Meridiani ~10 m]

No Float!

Outcrops OnlyInstructions on Door of JPL 183-803, 1998 to present

Occupant: T. Parker

No Float/OutcropGusev Hesperian Cratered Plains

Gusev Random Sample Hesperian CrateredPlains

Variable ThicknessImpact Generated Regolith

Likely Formed as Lava Flows

No Outcrop Found

Cratered

Plains

Cratered Plains

Angular Basalt

Fragments

Likely Basalt Flows

Impact Generated

Regolith

Bonneville

Fresh Crater, Fresh Ejecta, Little evidence for BackwastingNo Debris Chutes or Talus, Jumbled Regolith of Basalt Ejecta ~10 m ThickNo Outcrop

Viking Lander 1

Late Hesperian Cratered Surface

Limited Low Outcrop

Lot of Rock Float

No OutcropRocks are Float

Viking Lander 2

Lightly Cratered Surface forIntact Stratigraphy

Cratered Surface: Beware of Float, Regolith and No/Little Outcrop

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

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

Eolian Dune

Sand Sheet

Interdune

Sulfate (Gypsum) Evaporites in Playa Lake

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

Microbial Mat Textures Preserved in Evaporites

Example of Layered SulfatesHeadwaters of Maja VallesFloor Around -2 km Elevation4.5°S, 297.5°E

Juventae Chasma

4S

297E

5S

296.5E

Juventae Chasma Layered Deposits

Gypsum (Ca Sulfate)

Kieserite Mg Sulfate)

Stratigraphic Transition -Minerals with Different SolubilitiesBibring et

al. 2005

Land and Traverse on Sand SheetSample Stratigraphic Column

200 m

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

Example Distal Clay Rich SiteClinoforms

Channel

Clinoforms ClinoformsPrograding Delta

Prograding Clinoforms

Condensed Section, Decrease in Grain Size, Distal Clay RichEnhanced Organic Accumulation and Preservation

Prograding Clinoforms

Yellow Lines Define Single Depositional Sequence

Convergence of Clinoforms - Section CondensationDecrease in Grain Size

Accumulation of Clay Minerals and Organics

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)

Sequence Stratigraphy

Seismic Reflection Data - Prograding Clinoforms

Sequence Boundaries - Stratal Truncations and Onlap Define Cinoforma

Interpretation of Facies - Brown Shales, Downdip of Sands

Permian Clinoforms in Last Chance Canyon

Permian Clinoforms in Last Chance Canyon

Golombek & Grotzinger’s Guide 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