The Last Two Meters of Exhumation at Mount Sharp: Linking Rover-scale Geomorphology, Taphonomy, and Winds For submission to ROSES – MSL Participating Scientist Program 2015 (NNH15ZDA001N-MSLPSP) 1. Table of contents. ..................................................................................................................... 0 2. Scientific/Technical/Management. ......................................................................................... 1 2.1. Summary, Objectives, and Expected Significance. ........................................................ 1 2.2 Scientific Background. ....................................................................................................... 1 2.2.1. Exhumation processes link Mount Sharp geomorphology and climate ....................... 1 2.2.2. Taphonomy can be constrained by rover investigation of exhumation processes ....... 4 2.2.3. Winds’ role in exhumation can be constrained by rover investigation. ........................ 5 2.3 Technical Approach and Methodology. ........................................................................... 6 2.3.1. Stereo-Enabled Slope Analysis of Exhumation Susceptibility. ................................... 7 2.3.2. Mapping Aeolian-Exhumation Potential with Mastcam, REMS, and Modeling ......... 9 2.3.3. Assessing the Role of Late-Stage Weathering in Mount Sharp’s Exhumation ........... 11 2.3.4. Quantifying Exhumation’s Impact on Organic Matter Preservation Potential ........... 12 2.3.5. Assumptions and Caveats ............................................................................................ 14 2.4. Perceived Impact of the Proposed Work ......................................................................... 14 2.5. Relevance of Proposed Work to NASA Goals, MSL Goals, and MSL Mission-level Science Objectives. ........................................................................... 14 2.6. Work Plan. ........................................................................................................................ 15 2.7. Personnel and Qualifications. ........................................................................................... 15 3. References. ............................................................................................................................. 16 4. Biographical Sketch. .............................................................................................................. 28 5. Summary of Work Effort. .................................................................................................... 30 6. Current and Pending Support. ............................................................................................. 31 7. Statements of Commitment and Support. ........................................................................... 32 8. Budget Justification. .............................................................................................................. 34 8.1. Budget Narrative. ........................................................................................................... 34 8.1.1. Budget Analysis to Ensure That Participation in Daily Operations is Sufficiently Supported. ............................................................................................... 34 8.1.2. Facilities and Equipment. ............................................................................................. 37 8.2 Budget Details. ................................................................................................................... 38 9. Data Management Plan. ....................................................................................................... 41 The last two meters of exhumation at Mount Sharp: Linking rover-scale geomorphology, taphonomy, and winds 2. Scientific/Technical/Management: 2.1. Summary, Objectives, and Expected Significance. In what locations along MSL’s planned traverse have Mount Sharp’s rocks been exhumed over the last 106-109 years sufficiently rapidly to preserve complex organic matter? How has this exhumation been affected by microclimates, and differential rock resistance? To what extent have wind stress, abrader availability, and rare wetting events, controlled the pattern of exhumation? Motivated by the importance of exhumation as a control on taphonomy and as a proxy for climate-driven change, the broad objectives of this proposal are to analyze relief along the planned MSL traverse as a proxy for exhumation processes, determine the pattern of saltation-abrasion potential, and constrain the role of physical abrasion and aqueous processes in exhuming the rocks of Mount Sharp (Aeolis Mons). We will address these objectives through Mastcam, MAHLI and REMS measurements (of topography, rock texture, and winds), supported by modeling, with secondary contributions from DAN. The investigation requires participation in the science team to acquire specific measurements. Specifically, we will use Mastcam [Malin et al. 2010] and MAHLI [Edgett et al. 2012] images, and simple numerical models, to constrain landform degradation and erosional resistance. In parallel, we will use Mastcam image data, models, and REMS [Gómez-Elvira et al. 2012] observations, to carry out landform-scale mapping of saltation-abrasion potential. We will also use Mastcam, REMS, and the PI’s snowmelt model [Kite et al., 2013b], to quantify the possible role of aqueous fluids in exhumation. We shall thus obtain an improved understanding of the exhumation of sedimentary rocks at the <2m length scale and 106-109 yr timescale that are relevant to the preservation of complex organic matter and to geologically recent climate change. Locations with >2 m of geologically recent (<<109 yr) exhumation have improved potential to preserve complex organic matter [Farley et al. 2014, Grotzinger et al. 2014]. Given the importance of taphonomy to mission goals [MSL Extended Mission Plan 2014], improved understanding of exhumation – and identifying correlates of recent exhumation remotely and on an operational timescale – can enhance the science return from MSL. The proposed research will improve the science team’s ability to understand controls on recent exhumation by integrating data from multiple instruments and promptly comparing them to models. This can enhance the science return from SAM cosmogenic age-dating, by enabling predictions further along the traverse, and for future landing sites. The proposal builds on >8 years of experience by the PI with Mars microclimates, Mars erosion, and late-stage aqueous processes on Mars, and will leverage the PI’s existing funded project to study mountain-terrain effects on exhumation using the Mars meteorological model MRAMS (the PI has previously published papers using MRAMS; Kite et al. 2011a, 2011b) as well as the PI’s published models of Mount Sharp wind erosion and late-stage snowmelt at Mount Sharp [Kite et al. 2013b, 2013c]. Equally important to our proposed scientific investigation is our contribution to the success of the rover’s day-to-day operations, by providing scientists (the PI, a postdoc, and a graduate student) to serve in daily operational roles and assist in the acquisition of specific measurements. 2.2. Scientific Background. 2.2.1. Exhumation processes link Mount Sharp geomorphology and climate. Exhumation is necessary to form the moat that defines Mount Sharp, and to expose the mountain’s outcropping layers. Ongoing exhumation is suggested by Mount Sharp’s low crater density (Fig. 1) [Thomson et al. 2011]. Exhumation requires comminution of rock to fragments, 1 The last two meters of exhumation at Mount Sharp: Linking rover-scale geomorphology, taphonomy, and winds Extended Mission Exhumation Rates are Exhumation-Rate Variability Predicted to be Strongly Variable Matters for Taphonomy Crater Diameter (km) -2 -1 Organic Matter Surviving Radiolysis 10 10 100% 50% 0% 50% 100% 10-6 10-6 Ascent Canyons Mesa Tops Fan-Shaped Feature 500 amu Fractured Unit+Hummocky Plains Steady Exhumation 200 amu 10-7 EXTENDED MISSION(S) 10-7 113 EXTENDED amu MISSION(S) -8 113 amu: 0.01% -8 10 -17 10 500 amu: 10 % Crater-Obliteration Rate (m/yr) Single Resurfacing PRIMARY PRIMARY MISSION Kminek & Bada (2006) MISSION Equivalent Steady Exhumation Rate (m/yr) Dartnell et al. (2007) Hartmann (2005) crater !uxes. GCR only. Truncated at 0.13 km crater diameter. Farley et al. (2014) SCR neglected. Consistent with Sefton-Nash et al. (2014) adjusted to equivalent 500 amu values (dashed) and Newsom et al. (2015). steady exhumation. are extrapolated. 10-9 10-9 Fig. 1. Exhumation variability has significant implications for the preservation of complex organic matter. MSL’s Extended Mission will encounter terrains with higher crater-obliteration rates than terrain encountered during the Primary Mission. Crater-obliteration curves on Mt. Sharp are consistent with steady exhumation [Smith et al. 2008]. If steady exhumation is occurring (testable with Mastcam; §2.3.1) then enhanced organic-matter preservation potential is expected at Mount Sharp. For details, see §2.2.2 and §2.3.4. Phyllosilicates are mapped at the stratigraphic level of rapid crater obliteration [Thomson et al. 2011]. and surface shear stresses (wind or water) sufficient to export rock fragments from the mountain.1 Landscape-modification rates and processes can be interpreted using crater size- frequency distributions (CSFDs) (Fig. 1). CSFDs for Gale’s moat are well-explained by rare pulses of resurfacing [Newsom et al. 2015], in agreement