Venus - any chance for life?

1. Geology of Venus

2. Extant life on Venus

• Surface is 450°C - no water, highest extremeophiles grown @ 121°C. (~9.5 MPa pressure not a problem, organisms in Marinas trench ~100 MPa)
• But the clouds...,
  • shirt sleeve weather: 10 mbar to 2 bar, 240-390K.
  • high UV
    • 190% more incident than Earth, but albedo is also higher ~ Archean Earth
    • allotropic sulfur sunscreen?
  • concentrated sulfuric acid (82-98%wt, pH = 0) droplets and virga, volcanic SO₂ is oxidized to SO₃ + H₂O -> H₂SO₄. All water bound to SO₃. Acid is extremely dehydrating and oxidizing to organic molecules.
  • how would the organisms get there?
• Planetary Protection level 2 retained in 2006.

3. Ancient life on Venus

• Venus is very close to the habitable zone (Ask Prof. Herbst on Friday
• Venus D/H ~120 ± 40 X Earth (Pioneer Venus large probe) = >0.3% terrestrial ocean.
  • Venus may have started out dry, but hard to imagine next to such a wet neighbor.
• Mechanisms of water loss:
  • oxidation of minerals
  • Ion pickup by solar wind - more rapid in absence of magnetic field.
• Ocean persists 100s Ma? (Kasting 1988) 2 Ga? (Grinspoon and Bullock). f(clouds)

4. If you can't detect it, it doesn't matter

• Extant life in Venus clouds?
• Ancient life in Venus rocks?