Tori M. Hoehler NASA Ames Research Center

POP! BIG BANG A few things have to happen, and a few conditions must be met, to get from there to here. Understanding what these “things” and “conditions” are, and how frequently they occur, is astrobiology

The Road to Life? Habitability Origin of Life Chemistry Evolution and Continuity

Although we often think of them in cataclysmic terms, impacts and volcanoes are tied to the story of life in both negative and positive ways.

Heavily Cratered Surface Suggests Little Evidence of Recent Volcanism on Mercury

Radar Images Suggest Recent Volcanism on Venus

Active Rock Volcanism on Earth

Little Evidence of Volcanism on The Moon

Mars clearly had volcanism once, but how active is it now?

Sulfur Volcanism on Io

IceVolcanism on Enceladus?

Liquid Nitrogen Volcanism on Triton?

Volcanism is a way of transporting heat by moving material (when radiation or conduction just aren’t enough)

Bigger bodies cool more slowly, and may have more active or longer lasting volcanism as a result

Heat is transported by moving hot material from place to place – the material itself may be of great importance

On a differentiated planet, the hot material may come from a chemically different region

Volcanoes Bring Mantle Chemistry to the Surface Vent BiologyOrigin of Life Chemistry? Atmospheric (Stratospheric!) Chemistry Ocean CompositionCrustal Alteration

Creation of Atmosphere (example: Io)

Introduction of H 2 O and CO 2 (oceans and greenhouse)

Introduction of Sulfur and other “heteroatoms” (weather, salt balance, weathering)

Acids

Much of Earth’s “volcanic” activity occurs at the ocean bottom

Submarine volcanism is often manifested by transport of super- heated water (a great solvent, remember?)

= Salty Ocean Hydrothermal Alteration + Rock Weathering (Bases) Volcanic Outgassing (Acids) +

A chemically differentiated planet is like a battery... =

Hydrothermal vents transport chemical energy (they tap the Earth’s battery), and this can be harnessed by some microorganisms

Impacts...

Like volcanoes, impacts transport “stuff” from place to place

year century million yr. billion yr. ten thousand yr. 100 millionmillion10, Hiroshima Tunguska K/T TNT equivalent yield (MT) Global catastrophe Tsunami danger (Credit: D. Morrison) Size matters – and so does time Terrestrial Impact Frequency

Impact type matters, too

Impacts deliver energy (Sometimes a little, Sometimes a lot... )

Heat energy TitanEarth Apply heat here to make temporarily inhabitable? Apply heat here to make temporarily uninhabitable

Ejection of MaterialKinetic energy Release from Impacted Planet? Suspension in atmosphere?

Impacts deliver materials and chemistry from elsewhere in the solar system cometsasteroids

Volatiles are “frozen out” in the cold outer reaches of the solar system, and can be delivered to the inner solar system by comets Methane and nitrogen ice coat the surface of Triton

(Image credit: David Deamer) Impacts can deliver organic chemicals – possible importance for origins of life? Organics found in the Murchison meteorite form cell- like vesicles when they contact liquid water

E Effects of Impacts on Established Life: Impact Frustration of Life D’oh

year century million yr. billion yr. ten thousand yr. 100 millionmillion10, Hiroshima Tunguska K/T TNT equivalent yield (MT) Global catastrophe Tsunami danger (Credit: D. Morrison) Terrestrial Impact Frequency “Armageddon” Impact (Texas-sized!) “Catastrophic” depends on who you are and where you live...

Temperature (°C) Depth (km) Geothermal Gradient Surface-Sterilizing Impacts (Sleep & Zahnle, 1998) Habitable Heat-Sterilized Impact Heating

Effects of Impacts on Established Life: Interplanetary Transfer of Life?