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The Limits of Organic Life in Planetary Systems (2007) / Chapter Skim
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8 Conclusions and Recommendations
Pages 84-88

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From page 84...
... Different architectures at the microscopic and macroscopic levels must also be considered likely. Advocates of replicator-first theories hold that -- with reasonable interactions between minerals, polar refractory solvents, and organic species -- the spontaneous emergence of genetic biopolymers may be expected.
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From page 85...
... Some examples are growth in media with low ratios of water to organic solvents, the substitution of arsenic for phosphate, the use of carbon-silicon polymers, and the use of mineral catalysis instead of enzyme catalysis. • Further studies of chirality, particularly studies focused on the hypothesis that specific environmental conditions can favor chiral selection, or on an alternative model that life with L-amino acids and D-sugars is better "fit," from an evolutionary perspective, to evolve into complex organisms.
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From page 86...
... The discovery of evidence of liquid waterammonia eutectics on Titan provides a context for the potential for polar fluids outside what is normally regarded as the "habitable zone." The stay of the Cassini-Huygens mission on the surface of Titan was unfortunately brief; but this moon of Saturn is the locale that is arguably likely to support exotic life. Finally, the committee calls attention to the importance of using remote sensing to detect and characterize extrasolar planets that could support alternative carbon-based life.
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From page 87...
... Earth did not accumulate oxygen during the first roughly 3 billion years, and it did not form an ozone layer until about 1.5 billion years ago. There is considerable emphasis on looking for contemporary Earth atmospheres that have oxygen and an ozone layer, but there should also be models of atmospheres with different anaerobic microbial ecosystems, atmospheres that might parallel the different stages in the evolution of Earth's atmospheres over 4 billion years, and atmospheric conditions that could indicate the presence of a tectonically active planet.
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Key Terms

  • space studies
  • laboratory studies
  • darwinian evolution
  • weird carbon
  • energy sources

  • organic materials
  • novel metabolisms
  • extrasolar planets
  • atmospheric conditions
  • synthetic biology

  • extreme conditions
  • carbon life
  • organic carbon
  • analogous environments
  • especially studies

  • calls attention
  • permit returning
  • potential metabolic
  • committee offers
  • catalytic activity

  • include rna
  • sources thought
  • minerals set
  • extant extremophiles
  • single launch

  • active water
  • microbial ecosystems
  • detect lighter
  • water geysers
  • fractionates transition


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