Recommendation 17. NASA should take the following approach to preventing the forward contamination of Mars from Category III missions:

  1. Category III missions should be required to have orbital lifetimes of 20 years and 50 years, and the probability of impact over those time periods should be below 1 percent and 5 percent, respectively.

  2. Category III missions unable to meet these requirements should satisfy at least level 3 bioburden reduction requirements.

  3. For each Category III mission that cannot meet the orbital lifetime requirements, NASA’s planetary protection officer should appoint an independent, external committee with appropriate engineering, martian geological, and biological expertise to recommend to NASA’s planetary protection officer whether a higher level of bioburden reduction is required. This analysis should be completed by the end of Phase A for each mission. In reaching this determination, the appointed committee should consider previous experience, crash scenarios, and modeling for the mission, including the likely extent of release to the martian environment of organisms on nominally nonexposed surfaces or embedded in spacecraft components, as well as the presence and likely fates of radioisotope thermal generators or other sources of significant heat present on the spacecraft.

Chapter 9 presents a roadmap showing how the various recommendations fit together, as well as a time line for meeting the milestones that are required.


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