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Micro fossil in a meteorite ?

Micro fossil in a meteorite ?. (R. Hoover 2011). Lecture 7: Geologic History of Life. Oldest signatures of life in sedimentary rocks: Microfossils Molecular fossils (mainly lipids) Stromatolites C and S isotopic signatures Pattern of nested similarity. A fossil cyanobacterium

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Micro fossil in a meteorite ?

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  1. Micro fossil in a meteorite ? (R. Hoover 2011)

  2. Lecture 7: Geologic History of Life • Oldest signatures of life in sedimentary rocks: • Microfossils • Molecular fossils (mainly lipids) • Stromatolites • C and S isotopic signatures • Pattern of nested similarity A fossil cyanobacterium in circa 1.5 Gyr old sedimentary rocks - (A. Knoll).

  3. Microscopic fossils in ALH-84001 ?

  4. Methane release on Mars - 2009

  5. A hole on Mars ?

  6. Lecture 9: Habitable zones How do we define a habitable zone (HZ) ? The habitable zone in the Solar System. Life beyond the habitable zone ?

  7. Defining a Habitable Zone: Range of distances from the star where the temperature on some of the surface of a rocky planet allows water to be liquid. (The planet must have enough mass to keep an atmosphere.)

  8. Defining a Habitable Zone:

  9. The phase diagram of pure water:

  10. The phase diagram of pure water:

  11. Three important properties of water: Liquid in range of temperatures favorable to long-chain polymer forming; (2) Solid form (ice) floats in it own liquid - environmental stability; (3) Is a polar molecule - help membrane formation.

  12. The Terrestrial Planets Mercury Venus Earth Mars

  13. Mars - evidence for water

  14. Mars - evidence for water

  15. A changing Habitable Zone: HZ: shaded - now, dashed - once. The Sun, as all stars, evolves (burns its ‘fuel’ and changes structurally) - it will become cooler and larger.

  16. A changing Habitable Zone:

  17. A changing Habitable Zone:

  18. Beyond the HZ: Radiant heating from a parent star is not the only way to provide an energy source: Planetary interiors: radioactive & core heat Deep Biosphere Lab (Sweden): hyperthermophiles at depths of ~ 6 km (80 C). (2) Tidal heating

  19. Beyond the HZ: Titan

  20. Liquid CH4 & Water ice Liquid H2O & Silicate rock :Titan:::Earth Titan properties • 50% silicates, 50% ices; probably differentiated • Atmosphere is >90% N2 and 2-5% CH4 • Ts= 94K, Ps= 1.5 bar Near triple point Similar mechanical strength

  21. Lakes and channels on Titan!

  22. Main points to take home:

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