Mars Science—Where are our discoveries leading us? Nov. 19, 2008 David Beaty

File name: ScienceforMART9.ppt -

Discoveries: Geology The martian crust shows much greater geological diversity than previously thought. Erosion/Sedimentation: Periodic ancient burial and exhumation, complex sedimentary record involving multiple facies (fluvial, deltaic, evaporitic, aeolian, other?). Modern? (gullies). Complex Igneous History : Variety of volcanic landforms, mafic/ultramafic compositions--possibly also felsic compositions, some lava fields have very low crater densities--relatively recent eruptions? Products of Water/Rock Interaction: Secondary silica, diagenetic minerals (e.g. hematite concretions) in the sedimentary rocks, sulfate-rich alteration, clay minerals in variety of settings. Impact Processes: M ultiple relationships with the above . Modern water, relation to surface chemistry Water is present on Mars today in extensive shallow deposits of ground ice, in low-latitude glacial deposits, in hydrous minerals, and in both polar caps. Planetary Differentiation Early, rapid crystallization of a magma ocean (10-50 my). -

The martian crust shows much greater geological diversity than previously thought.

Erosion/Sedimentation: Periodic ancient burial and exhumation, complex sedimentary record involving multiple facies (fluvial, deltaic, evaporitic, aeolian, other?). Modern? (gullies).

Complex Igneous History : Variety of volcanic landforms, mafic/ultramafic compositions--possibly also felsic compositions, some lava fields have very low crater densities--relatively recent eruptions?

Products of Water/Rock Interaction: Secondary silica, diagenetic minerals (e.g. hematite concretions) in the sedimentary rocks, sulfate-rich alteration, clay minerals in variety of settings.

Impact Processes: M ultiple relationships with the above .

Modern water, relation to surface chemistry

Water is present on Mars today in extensive shallow deposits of ground ice, in low-latitude glacial deposits, in hydrous minerals, and in both polar caps.

Planetary Differentiation

Early, rapid crystallization of a magma ocean (10-50 my).

Discoveries: Climate Early climate change Early climate supported extensive alteration of the surface/near-surface by liquid water Major alterations in surface chemistry seem coincident with decline of the global magnetic field. Water activity was intermittent: Different layers show different kinds of minerals, indicating evolution over time but also periods of little compositional alteration Modern climate change Layered patterns in the polar ice caps, mid-latitude ice deposits, and very regular layered deposits elsewhere argue for recent quasi-periodic climate change Analog between Mars and Earth: Changes on a human time scale? Subsurface Processes Methane detection/hypothesis argues for active interior and tectonic activity which enables exchange between crust and atmosphere -

Early climate change

Early climate supported extensive alteration of the surface/near-surface by liquid water

Major alterations in surface chemistry seem coincident with decline of the global magnetic field.

Water activity was intermittent: Different layers show different kinds of minerals, indicating evolution over time but also periods of little compositional alteration

Modern climate change

Layered patterns in the polar ice caps, mid-latitude ice deposits, and very regular layered deposits elsewhere argue for recent quasi-periodic climate change

Analog between Mars and Earth: Changes on a human time scale?

Subsurface Processes

Methane detection/hypothesis argues for active interior and tectonic activity which enables exchange between crust and atmosphere

Discoveries: Life Habitability: Lots of evidence of liquid water activity, surface and ground: Fluvial landforms, aqueous minerals, sedimentary rocks Biologically available energy: several possibilities Organic carbon: TBD (MSL, ExoMars) Alkaline, as well as acidic, environments Some environments appear to have reasonable potential to preserve biosignatures: Rapid and massive deposition (Eberswalde, Gale, etc.) Mineral diversity (Mawrth Vallis, Nili Fossae, etc.), including the detection of some carbonate in intact bedrock (not dust) and possible salt beds Modern life—still possible Methane—a potential biosignature? (spatial variation?) Geologically young ice deposits: Polar ice caps with few craters, high-latitude ice within centimeters of the surface, buried ice deposits (within 0.5 km of surface) in mid-latitudes -

Habitability:

Lots of evidence of liquid water activity, surface and ground: Fluvial landforms, aqueous minerals, sedimentary rocks

Biologically available energy: several possibilities

Organic carbon: TBD (MSL, ExoMars)

Alkaline, as well as acidic, environments

Some environments appear to have reasonable potential to preserve biosignatures:

Rapid and massive deposition (Eberswalde, Gale, etc.)

Mineral diversity (Mawrth Vallis, Nili Fossae, etc.), including the detection of some carbonate in intact bedrock (not dust) and possible salt beds

Modern life—still possible

Methane—a potential biosignature? (spatial variation?)

Geologically young ice deposits: Polar ice caps with few craters, high-latitude ice within centimeters of the surface, buried ice deposits (within 0.5 km of surface) in mid-latitudes

WHAT’S NEXT? Where are our discoveries leading us? Ancient life—encouragement probably increasing Modern life—still possible? How do we access the sites to test? Environments—how and why do they vary, when and why do they change? Comparative planetology—especially Mars-Earth; understand Mars as a system -

Ancient life—encouragement probably increasing

Modern life—still possible? How do we access the sites to test?

Environments—how and why do they vary, when and why do they change?

Comparative planetology—especially Mars-Earth; understand Mars as a system