time, the framework provides a platform for incorporating new observational data from planetary exploration missions and the latest information about microbial physiology and metabolism, particularly for psychrophilic (i.e., cold-loving microbes) and psychrotolerant microorganisms.
The committee’s third task concerned the identification of scientific investigations that could reduce the uncertainty in the above estimates and assessments, as well as technology developments that would facilitate implementation of planetary protection requirements and/or reduce the overall probability of contamination. The committee recognizes the requirement to further improve knowledge about many of the parameters embodied within the decision framework. Areas of particular concern for which the committee recommends research include the following:
• Determination of the time period of heating to temperatures between 40°C and 80°C required to inactivate spores from psychrophilic and psychrotolerant bacteria isolated from high-latitude soil and cryopeg samples, as well as from psychrotolerant microorganisms isolated from temperate soils, spacecraft assembly sites, and the spacecraft itself.
• Studies to better understand the environmental conditions that initiate spore formation and spore germination in psychrophilic and psychrotolerant bacteria so that these conditions/requirements can be compared with the characteristics of target icy bodies.
• Searches to discover unknown types of psychrophilic spore-formers and to assess if any of them have tolerances different from those of known types.
• Characterization of the protected microenvironments within spacecraft and assessment of their microbial ecology.
• Determination of the extent to which biofilms might increase microbial resistance to heat treatment and other environmental extremes encountered on journeys to icy bodies.
• Determination of the concentrations of key elements or compounds containing biologically important elements on icy bodies in the outer solar system through observational technologies and constraints placed on the range of trace element availability through theoretical modeling and laboratory analog studies.
• Understanding of global chemical cycles within icy bodies and the geologic processes occurring on these bodies that promote or inhibit surface-subsurface exchange of material.
• Development of technologies that can directly detect and enumerate viable microorganisms on spacecraft surfaces.
1. United Nations, Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, U.N. Document No. 6347, Article IX, January 1967.
2. M. Meltzer, When Biospheres Collide: A History of NASA’s Planetary Protection Programs, NASA SP-2011-4234, NASA, Washington, D.C., 2011.
3. National Research Council, Preventing the Forward Contamination of Europa, National Academy Press, Washington, D.C., 2000.
4. National Research Council, Preventing the Forward Contamination of Europa, National Academy Press, Washington, D.C., 2000.
5. The recommendation to accept the 10–4 criterion was made at the 7th COSPAR meeting in May 1964 (see COSPAR, Report of the Seventh COSPAR Meeting, Florence Italy, COSPAR, Paris, 1964, p. 127, and, also, COSPAR Information Bulletin, No. 20, November, 1964, p. 25). The historical literature does not record the rationale for COSPAR’s adoption of this standard. Subsequent policy changes restricted the 10–4 standard to Mars missions (COSPAR, “COSPAR Planetary Protection Policy (20 October 2002; As Amended to 24 March 2011),” COSPAR, Paris, p. A1, available at http://cosparhq.cnes.fr/Scistr/PPPolicy%20(24Mar2011).pdf.
6. COSPAR Panel on Planetary Protection, COSPAR Workshop on Planetary Protection for Outer Planet Satellites and Small Solar System Bodies, European Space Policy Institute, Vienna, Austria, 2009.
7. COSPAR Panel on Planetary Protection, COSPAR Workshop on Planetary Protection for Titan and Ganymede, COSPAR, Paris, France, 2010.