the eighth international conference on mars...– sand dune migration and associated erosion. –...

Synthesis Presentations and Discussions

Chair: Lisa Pratt (Indiana University) Geology: Phil Christensen (Arizona State University) Climate: Rich Zurek (NASA Mars Program Office, JPL/Caltech) Life: Dave Des Marais (Ames Research Center) Future Exploration: Marcello Coradini (European Space Agency)

The Eighth International Conference on Mars

July 14-18, 2014 Pasadena, California

Emergence of Mars System Science

Shared Odd Vocabulary: Remnant magnetic field Black Beauty Ultramafic serpentinization Mineral deliquescence Late Noachian icy highlands Transient Hesperian water Perchlorates Gray-scale habitability RSL (do not attempt to say words) Swiss-cheese pit cycle Katabatic jumps in troughs Detached dust layers

Rosetta-Stone Images

Bibring’s mineral timescale Laskar’s obliquity cycles

Pratt, 8th Mars Conference

Memorable Quotes Modern Mars should be much easier to understand than ancient

Mars

A balancing act between a variety of processes which can be easily swayed (inclination)

Explanations for present-day Mars are the key to understanding past processes on Mars

Much is known, less is understood

Hopefully, by 9th Mars we will have it all solved

Pratt, 8th Mars Conference

Reflections on the State of Mars Geology

Phil Christensen

Mike Kraft Mark Salvatore

Arizona State University

Kristen Bennett

Arizona State University

Lonia Friedlander Stony Brook University

Rebecca Greenberger Brown University

Where We Were in 2008 – MEPAG Goals • A. Determine the nature and evolution of the geologic processes that have

created and modified the Martian crust – Determine the formation and modification processes of the major geologic

units and surface regolith as reflected in their primary and alteration mineralogies.

– Evaluate volcanic, fluvial/lacustrine, hydrothermal, and polar erosion and sedimentation processes.

– Constrain the absolute ages of major crustal geologic processes. – Hydrothermal environments. – Evaluate igneous processes and their evolution through time. – Characterize surface-atmosphere interactions on Mars. – Determine the tectonic history and large-scale vertical and horizontal

structure of the crust. – Determine the present state, 3-dimensional distribution, and cycling of

water on Mars. – Determine the nature of crustal magnetization and its origin. – Evaluate the effect of large-scale impacts on the evolution of the Martian

crust. • B. Characterize the structure, composition, dynamics, and evolution of Mars’

interior – Characterize the structure and dynamics of the interior. – Determine the origin and history of the magnetic field. – Determine the chemical and thermal evolution of the planet.

Christensen, 8th Mars Conference

Advances

• Mineralogic diversity and distribution

• Knowledge of current water inventory

• Real-time observations of modern, dynamic Mars

• Climate cycling: Snow, ice, liquid water, dust, CO2, S…

• Observations of multiple sites at “field geologist” scale

• Potential variations in early volcanic processes

• Interior processes connect to surface processes

• Growing awareness of the impact of impacts

• New techniques, integration of multiple data sets, and cross-disciplinary studies


Key Questions

Overarching question: Time

• Water: activity, state, duration…?

• Is there a martian rock cycle? And where are we in it?

• What is the role of wind? Large impacts?

• What is the petrologic context of key mineral detections?

• Amorphous materials: How do they form? What do they mean?

• Nature of early volcanism – Explosive? Friable ash deposits?

• What were the processes of the pre-Noachian?

• How does Uniformitarianism apply to Mars?

– To what degree do currently active processes explain the past?


Going Forward • Mineral assemblages: era of mineralogy to era of petrology

– Geochemistry, context, and textures

– Currently explaining what we can measure

» “Lost key” model of mineralogic interpretation

» But we’ve only lit up part of the street

• We know liquid water interacted with rock – but:

• How warm? How wet? How long? How much? How come? Where?

• Test competing hypotheses

– Fully utilize and integrate data sets

• Fill the gap between global and “outcrop” mapping

• Appreciate the potential for spatial variability

• Global phenomena… regional consequences… local effects

• Continue to use geology as ground truth for climate and interior evolution models


Climate Richard Zurek

JPL-Caltech

Todd Mooring Princeton University

Scott Guzewich GSFC

Michael Chaffin University of Colorado

Nature of the Early Massive Atmosphere Draw-down of the early, more massive atmosphere:

– When did it happen and how fast? – How long was water on/near the surface, &where did it go?

• Atmospheric Characterization: – Warm/Wet early Mars is not an option if Solar luminosity was 75% of present

value.* Do we really need rain? – Intermittently Warm/Wet may still be in play, but requires exceptional

combinations (e.g., maybe trace gases + obliquity extremes). – Cool/Wet looks possible, but lots of details to be worked out. Models appear

capable of simulating spatially varying deposition of snow/ice—the question is how does this get turned into liquid and produce the needed compositional alteration?

• Looks like the water budget (sources ~ sinks) still has missing components. Need a better understanding of escape processes (go MAVEN!).

• Major Progress: At 7th Mars, aqueous minerals indicated water was present (follow the water). Since then, the diversity of minerals detected points to different environmental regimes (T, water, pH, time). Need better spatial/temporal constraints. E.g., was there really more water activity in the late Noachian or has evidence of earlier activity been partially erased?

*Vigorously contested during discussion period

Zurek, 8th Mars Conference

Circulation and Transport Dictated by Astronomical Cycles – Dust and water cycles at different obliquities, eccentricities & seasonal phasing – Changing water, dust, and atmospheric gas inventories

• Major Progress: We can now see the record of the polar layered terrains. Radar has revealed the inner structure of the polar caps. In the young (<10 Myr) NPLD there are regular patterns (layer packets) that appear to reflect obliquity cycles. Need to connect cause and effect for the NPLD in a more quantitative way. Need to understand the longer record of the SPLD and put it in context with the north. – Polar troughs: Story seems well in hand—major confirmation of early

ideas both qualitatively and semi-quantitatively. • Major Find: CO2 ice buried in the (south) polar caps

– Some ideas about how to do this and what it could mean if released back into the atmosphere. Need to pursue and test these ideas.

• Major Progress: Buried ice/snow—we know it’s there in some places. How extensive, how deep? Where are the shallow ice boundaries in latitude, south as well as north?

• Are there implications here for the Noachian & Hesperian, as well as Amazonian periods?


Modern Mars: Still Changing Today • Major Progress: Continued observations show a dynamic planet, still

changing today, with significant interannual variability (dust storms, CO2 polar ice, etc.) and more: – 8 Mars years of Temperature, column dust and water vapor – RSL (see below) – Seasonal CO2 acting to form/enhance high latitude gullies – Sand dune migration and associated erosion. – Need to extend the observation period

• Major Progress: Observations now show the vertical structure of dust, of temperature (tides), and of water vapor and ice. Getting these right is vital to getting the circulation and transport right. Need better vertical resolution near the surface. Need to get independent measurements of T/water and of dust.

• Major Course Correction: Clouds (and cloud physics) have to be taken into account.

• Major Discovery: RSL suggest generation of liquid water (brines) today over a surprisingly large number of places on Mars. What are these, really? How do we test this hypothesis?


Tools • GCMs = Global Climate Models

– Major Progress: • Vertical/spatial resolution much higher than a decade ago • Transport schemes; interactive processes (e.g., radiatively active dust);

photochemical • Parameterizations of key processes: exchanges with surface, cloud

physics, photochemistry

– More Progress Needed • Better spatial resolution • Better physics • More validation => More observations and different observations (e.g.,

winds)

Gaps • Electrical environment • Photochemical system (TGO will help)

– Still issues with oxidation states (and not just of the atmosphere) and basic photochemistry (why is the atmosphere still CO2?)

• Instruments


8th Intl. Conf. on Mars Life Synthesis Presentation

Jennifer Buz California Institute of Technology

Caroline Freissenet Goddard Spaceflight Center

Rebecca Mickol University of Arkansas

Scott Perl JPL and USC

Marek Slipski University of Colorado

Svetlana Shkolyar Arizona State University

David J. Des Marais Ames Research Center

solutes

demand supply

extremes impose

costs

solubility

Des Marais, 8th Mars Conference

Important Findings Since 7th Mars

• Water – Extensive ancient networks & lakes – precipitation – Aqueous minerals in diverse settings – Transient events affecting abundance throughout history

• Ingredients for life – Readily available, even trace nutrients – Local enrichments in key elements (e.g., P, Mn, Zn) – Organics found by SAM

• Energy – Ancient wet, sunlit environments were not rare – Redox energy available – documented redox pairs – Radiation from nuclear decay might sustain subsurface life


Important Findings Since 7th Mars (continued)

• Conditions – Ancient aqueous conditions over extended periods – Thermal spring localities found – Evidence for more neutral pH environments – Evidence for high W/R ratios remains uncommon

• Preservation – Deposits favoring potentially excellent preservation -

phyllosilicates, silica, carbonates, Fe oxides – Organic preservation demonstrated by MSL SAM – Radiation at the martian surface has been quantified -

challenges organic preservation and any near surface life

Important Remaining Questions • Water

– Spatial/temporal distribution: surface, subsurface? – Where was chemical water activity (Aw) sufficient for life? – Was persistence sufficient for origins & evolution?

• Ingredients for life – Geochemical cycles of biogenic elements? – Crustal abundance & attributes of organic building blocks?

• Energy – Was availability of free energy & power adequate? – Might subsurface life be viable in face of energy limitation?

• Conditions – Distribution of aqueous environments at various pHs? – What range of W/R is habitable?

• Preservation – Which martian rock types are most suitable for preservation? Can

these be sensed from orbit? – How can radiation hazards to preservation be avoided?


Important Remaining Questions (continued)

• Life/Biosignatures – How can we recognize evidence for life as we don’t know it? – How can we confirm biosignatures in Martian habitable contexts

(“signal to noise” challenge)? – How can we obtain parallel lines of consistent evidence most effectively

– multiple instrumentation, need for MSR • Extant life

– Where should we look, given the current evidence for pervasive harsh conditions in surface environments?

– What spacecraft could have the capability to access and explore a recently habitable and potentially inhabited environment (e.g., higher latitudes)?

– Which measurements are most effective to detect life? Combination of techniques for biosignatures, labile bioorganics & metabolic assays?

– What methods for resolving contamination from actual Martian features are most effective?


What Can We Do to Find Answers? • Site selection - potential past habitable environments

– Continue observations by current orbital assets – Research to improve understanding of relationships

between remotely sensed features & habitability parameters

• Spacecraft/technology capabilities – Improve EDL capabilities to access most scientifically

compelling sites • Flight measurements in situ

– Characterize environmental context of key samples – Improve in situ measurements of potential biosignatures – Improve contamination identification methods

• Earth-based analog studies to improve exploration – Focus on Mars-relevant processes & strategies Des Marais, 8th Mars Conference

What Can We Do to Find Answers? (cont.)

• Extant life – Locate & validate any promising sites for extant life (e.g.,

vents? Higher latitude sites?) – Develop concepts for spacecraft that could access &

explore a recently habitable & potentially inhabited environment (e.g., higher latitude sites?)

– Refine measurements to detect life, including life as we don’t know it. (e.g., instrument suite for multiple lines of evidence: various biosignatures & metabolic assays?)

– Develop more effective methods for resolving Earth contamination from Martian components

• Sample Return – Develop sample handling & curation facilities – Improve methods for analyses of returned samples


Extending our Concepts of Life

• Origins of Life – What conditions & events allowed the key components of

living system(s) to develop? – What environmental & evolutionary paths led to the

attributes shared by all modern life? • Determinism

– Do “nurturing” environments often lead to life? – To what extent do physical & chemical factors cause life

elsewhere to resemble our own? • Diversity

– Is Earth’s biosphere a subset of a greater diversity of life in the universe?

– What are life’s ultimate environmental limits?


Preparation for Human Exploration

Marcello Coradini Simon Engler

Suzanne Gordon Kennda Lynch Maurizio Pajola Steven Sholes

Robotic Missions

Human Missions

Mars Exploration: forward to the past! tim

e

today

2020

2030

2040 Hazards

Contamination

Resources

Knowledge

• 2nd/3rd gen global DEM • Hi-Res Mineralogy (Orbit/ground) • In Situ Age determination • Stratigraphic Exploration • Internal Structure • Chronology of Atm. Evolution & Meteo • Hi-Res Magnetic mapping (& Paleo)

Energy H2O

O2

Fuel

Bio

Chem., Meteo., Environm., etc.

Cube Orbiter swarms

Surface diversity missions

Gravity and magnetic orbiters

Sample Return Missions

No

prio

rity

Coradini, 8th Mars Conference

the eighth international conference on mars...– sand dune migration and associated erosion. –...

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