Mars Landing Sites: Mawrth Vallis. Debra Buczkowski, Kim Seelos, Wes Patterson, and Frank Seelos

Transcription

1 Mars Landing Sites: Mawrth Vallis Debra Buczkowski, Kim Seelos, Wes Patterson, and Frank Seelos

2 Review: Final 4 (or 5?) Candidate MSL Landing Sites Northeast Syrtis Eberswalde Crater Mawrth Vallis + one of these may be added at Sept workshop Holden Crater Gale Crater East Margaritifer 2

3 Review: MSL Landing Site Selection Requirements Engineering Constraints Latitude ± 60 Elevation 2 km Ellipse size km Slopes 3-15 (depends on length scale) Rock height/abundance 0.6 m/low to moderate Winds m/s (depends on direction and altitude) Radar reflectivity >-20 db Load bearing surface moderate-high thermal inertia, low albedo = not too dusty Science Rationale Eplore and quantitatively assess a local region on Mars surface as a potential habitat for life, past or present Contet What is the age and geologic setting of the site? Possible for observations made by the rover to be put into regional contet? Diversity of science targets Are there multiple depositional settings or mineral assemblages to investigate? Habitability Does the mineralogic and morphologic evidence support a habitable environment? Biopreservation potential What minerals or depositional structures are present that might preserve ancient signs of life? 3

4 Where is Mawrth Vallis? 24.01ºN ºE -2.2 km Mawrth Vallis + many more! 4

5 What s so interesting about Mawrth? OMEGA on Mars Epress was the first to discover widespread layered phyllosilicates in Mawrth Vallis OMEGA is similar to CRISM, but lower spatial resolution Several candidate MSL sites chosen in region HRSC mosaic Unit sketch map 5

6 What s so interesting about Mawrth? OMEGA on Mars Epress was the first to discover widespread layered phyllosilicates in Mawrth Vallis OMEGA is similar to CRISM, but lower spatial resolution Several candidate MSL sites chosen in region OMEGA hydration red = highest concentration Hydration (1.93 μm) Mg/Fe rich phyllosilicate (2.30 μm) 6 Al-OH rich phyllosilicate (2.20 μm)

7 Ellipse size need a safe spot to land Regional slope map Scale = 926 m Red = steep White circles indicate 4 initial sites, all in areas where slopes are good for landing at this length scale Downselected site 7

8 Science Rationale Evaluating Mawrth Vallis Lithologic contet of the phyllosilicate clays? Age? Stratigraphic contet? Likely to preserve biomarkers? Understandable? Primary formation modes of phyllosilicates and pathways in between 8

9 Mawrth Vallis Geologic Units Light-toned bedrock is layered, diverse, and comple and deposited over geologically significant duration of time 9

10 HiRISE Images of Light-toned Layers Layered materials are widespread, contiguous 10

11 HiRISE image of landing site Same light-toned layers observed regionally Also notice that there are few, or no, rocks 11

12 HiRISE image of landing site 12

13 Mawrth Stratigraphy Light-toned unit has several subunits Most clay-bearing, but not all Dark-toned unit unconformably overlies light-toned unit 13

14 Evaluation of Light-toned Unit Deposited over a geologically significant period of time Impact craters buried within unit Not deposited in a single catastrophic event Heavily eroded Possibly in the late Noachian Lithified early Clays formed early 14

15 Clays are demonstrably associated with a layer that is: Origin of the Clays Thick Flat-lying Ancient Widespread, undeformed Geomorphically comple Deposited over a long time period 15

16 Origin of the Clays Clay mineral origin not consistent with: Impact origin Epect instantaneous event Less complete section of rocks Recent subaerial weathering Epect diffuse pattern of surface composition Hydrothermal alteration associated with intrusion Epect localization Ties to structure/permeable conduits 16

17 Origin of the Clays Clay mineral origin not consistent with: Low temperature alteration of lavas Not consistent with volcanic structures Regional metamorphism Requires deep burial and reeposure Epect to see deformation Deep marine environment Difficult to reconcile with repeated subaerial eposure 17

18 Favored interpretation: Sedimentary origin at/near surface Clays deposited as sediments (or cements) Sediments could be of volcanic (pyroclastic) origin Associated with sustained dynamic surface environment River, lake, or shallow sea Diagenetic processes cannot be ruled out Diagenesis is alteration of minerals after deposition Even if diagenetic, clays are OLD! Origin of the Clays Indicates that early Mars had a much different environment than now 18

19 Summary of Mawrth Science Merits 1) Thick comple section gives plenty to eplore, but is intact and understandable 2) Clays are as widespread, abundant and diverse Within landing ellipse do not need to go-to Chance of preserved biomarkers Possibly deposited in fluvial system or shallow marine environment Clays could have formed in shallow subsurface diagenesis 3) Uncertain geologic origins, but testable by MSL Imaging will show bedding structures, grain shapes, overall rock teture Bulk chemistry will show stratigraphic variation In situ identification of minerals Could show organics trapped in a variety of contets 19

20 Engineering and Science Constraint Checklist Engineering Constraints Latitude ± 60 Elevation 2 km Ellipse size km Slopes 3-15 (depends on length scale) Rock height/abundance 0.6 m/low to moderate Winds m/s (depends on direction and altitude) Radar reflectivity >-20 db Load bearing surface moderate-high thermal inertia, low albedo = not too dusty Science Rationale Eplore and quantitatively assess a local region on Mars surface as a potential habitat for life, past or present Contet What is the age and geologic setting of the site? Possible for observations made by the rover to be put into regional contet? Diversity of science targets Are there multiple depositional settings or mineral assemblages to investigate? Habitability? Does the mineralogic and morphologic evidence support a habitable environment? Biopreservation potential What minerals or depositional structures are present that might preserve ancient signs of life? 20?

21 Multispectral PHY browse map Red = Fe/Mg phyllosilicates Green = Al phyllosilicates Blue = Hydration CRISM Quickmap view 21

22 Targeted coverage Red = FRT Green = HRL Blue = HRS Many CRISM images acquired of potential Mawrth landing sites CRISM Quickmap view 22

23 CRISM-map View CRISM verifies OMEGA results + more abundant and diverse phyllosilicates and other hydrated minerals in the region Net slide CRISM-map showing regional coverage of hyperspectral targeted images 23

24 CRISM-map PHY browse products Red = Fe/Mg phyllosilicates Green = Al phyllosilicates Blue = Hydration HRS 1176A FRT 117BB FRT 89F7 FRT BB59 FRT B141 FRT A600 FRT B643 HRL 11CDD 24

25 Landing site mineralogy from CRISM Orange = Nontronitebearing Yellow = nontronite plus a ferrous component Green = montmorillonite/ hydrated silica plus a ferrous component Cyan = montmorillonite/ hydrated silica Blue = kaolinite from McKeown et. al. (2009) 25

26 Mineral stratigraphy (A) CRISM and lab spectra from images HRL000043EC (B) Perspective mineral indicator map Orange/Red = Fe/Mgsmectite Blue = hydrated silica Yellow/Green = Fe 2+ phases (C) Sketch stratigraphy of phyllosilicates using the colors from (B). (D) Portion of HiRISE image showing tetures of different layers from Bishop et. al. (2008) 26

27 OK, so what now? Using the CRISM web tools, look for outcrops of distinct, spatially coherent deposits of phyllosilicates, sulfates, or other hydrated mineralogy Minerals that have been influenced by water, and thus may reveal something about the ancient history or climate of Mars, or may preserve biosignatures If you find an interesting location, use other data sets to evaluate whether it may make a good landing site based on the engineering constraints we ve talked about E.g., a cliff would not be a good landing site even though there may be great eposures of phyllosilicates in the walls Although it is too late to be considered for an MSL landing site, any interesting places that you discover could become a future landing site, sample return site, or human settlement site Often the candidate sites that make it to the final round of consideration have been in study for a long time 27

28 For Further Reading and Reference Documentation of MSL landing site selection workshops and available data sets: Recommended presentations from Third MSL Landing Site Workshop Geomorphic Criteria for Defining Depositional Setting by Alan Howard Preservation of Organic Matter in Phyllosilicates by Lisa Pratt And others in that section NASA ADS reference search tool: CRISM web tools CRISM map: Quickmap: Username: sciteam password: yourstuff1 Contet datasets Mars Orbital Camera (MOC): Thermal Emission Imaging System (THEMIS): High Resolution Imaging Science Eperiment (HiRISE): USGS : Nomenclature (does that crater have a name?) 28