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Assessment of Planetary Protection Requirements for Spacecraft Missions to Icy Solar System Bodies (2012) / Chapter Skim
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3 Hierarchical Decisions for Planetary Protection
Pages 19-22

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From page 19...
... If the target site does not provide these basic needs, mission planners do not have to take special precautions normally associated with preventing forward contamination beyond the routine clean ing and monitoring of spacecraft. This approach restricts the number of bodies of concern for planetary protection requirements.
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From page 20...
... 8 In the terrestrial deep subsurface, some sources of electron donors and acceptors, such as the production of hydrogen by radiolysis of water, show that extreme geophysical environments analogous to those on icy bodies in the outer solar system can be the source of half reactions. In contrast to potential sources of chemical energy, light capture would not provide a useful energy source for terrestrial life forms on the surfaces of, or beneath the thick ice shells of, planetary bodies in the outer solar system.
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From page 21...
... CONCLUSIONS AND RECOMMENDATIONS A series of decision points based on constraints defined by the preponderance of available scientific data or new information from future missions and research provide a robust mechanism for evaluating planetary protection requirements. The first and most critical decision point must consider whether liquid water is not available, fol lowed by decision points describing the lack of availability of building blocks including the key elements carbon, nitrogen, phosphorus, and so on -- the absence of environmental parameters known to be compatible with the growth of terrestrial life -- and finally the lack of available energy sources required for terrestrial life.
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From page 22...
... Phillips, Novel mode of microbial energy metabolism: Organic carbon oxidation coupled to dissimila tory reduction of iron or manganese, Applied and Environmental Microbiology 54:1472-1480, 1988.
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Key Terms

  • terrestrial life
  • icy bodies
  • liquid water
  • mission planners
  • chemical energy

  • protection requirements
  • icy body
  • target body
  • support terrestrial
  • outer solar

  • requires liquid
  • energy sources
  • future missions
  • biological exploration
  • electron transport

  • electron donors
  • temperature range
  • terminal bioload
  • bioload reduction
  • life forms

  • range relates
  • target site
  • nutrient conditions
  • target icy
  • equally unlikely

  • criteria outlined
  • double stranded
  • below minimal
  • radiation fluxes
  • aquatic environments


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