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Assessment of the Report of NASA's Planetary Protection Independent Review Board (2020)

Chapter:Appendix E: Planetary Protection Categories

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Suggested Citation:"Appendix E: Planetary Protection Categories." National Academies of Sciences, Engineering, and Medicine. 2020. Assessment of the Report of NASA's Planetary Protection Independent Review Board. Washington, DC: The National Academies Press. doi: 10.17226/25773.
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E

Planetary Protection Categories

TABLE E.1 Mission Type Categories as Specified in COSPAR’s Planetary Protection Policy

Mission Category Mission Type Planetary Bodies Planetary Protection Requirements (Illustrative Examples)
I Any Bodies not of direct interest for understanding the process of chemical evolution or the origin of life (e.g., undifferentiated, metamorphosed asteroids, and others [to be determined]). None
II Any Bodies of significant interest relative to the process of chemical evolution and origin of life, but only a remote chance that contamination could compromise future investigations (e.g., comets, carbonaceous chondrite asteroids, outer solar system planets, Venus, the Moon, icy bodies of the outer solar system [note 1] and others [to be determined]). Brief documentation only (except for missions to the Moon, which also require an inventory of all organic compounds present in excess of 1 kg).
III Flyby, orbiter (no direct contact) Bodies of significant interest to the process of chemical evolution and/or origin of life and where scientific opinion provides a significant chance that contamination could compromise future investigations (e.g., Mars [note 2], Europa, Enceladus, and others [to be determined]). Documentation on contamination control and organics inventory, plus trajectory biasing, cleanroom, bioload reduction.
IV Lander, probe (direct contact) Bodies of significant interest to the process of chemical evolution and/or origin of life and where scientific opinion provides a significant chance that contamination could compromise future investigations. (e.g., Mars [note 3], Europa, Enceladus, and others [to be determined]). Documentation (as for cat. III) plus microbial reduction plan; cat. III procedures plus partial sterilization and bioassay monitoring.
V (unrestricted) Earth return after contact with another body Earth-return missions from bodies deemed by scientific opinion to have no indigenous life forms (e.g., Venus, Moon, and others [to be determined]). None except for requirements for category above for outbound phase.
V (restricted) Earth return after contact with another body Earth-return missions from bodies deemed by scientific opinion to be of significant interest to the process of chemical evolution and/or origin of life (Mars, Europa, and others [to be determined]). Same as for cat. IV plus sterile or contained returned hardware and continual monitoring of project activities.
Suggested Citation:"Appendix E: Planetary Protection Categories." National Academies of Sciences, Engineering, and Medicine. 2020. Assessment of the Report of NASA's Planetary Protection Independent Review Board. Washington, DC: The National Academies Press. doi: 10.17226/25773.
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Mission Category Mission Type Planetary Bodies Planetary Protection Requirements (Illustrative Examples)
Note 1 Missions to Ganymede, Titan, Triton, Pluto/Charon, and Kuiper belt objects greater than half the diameter of Pluto can be assigned to Category II if they demonstrate by analysis their “remote potential for contamination of the liquid-water environments that may exist beneath their surfaces (a probability of introducing a single viable terrestrial organism of <1 × 10−4) addressing both the existence of such environments and the prospects of accessing them.”
Note 2 Mars orbiters are required to meet an orbital lifetime requirement (20 or 50 years after launch with a probability ≥0.99 or 0.95, respectively. Lifetime requirements are not required if the orbiter meets a total bioburden level of ≤500,000 spores.
Note 3 Category IV missions to Mars are subdivided into IVa, IVb, and IVc. Category IVa missions—i.e., those not carrying instruments designed to investigate extant martian life—are restricted to a surface bioburden of ≤300,000 spores, and an average of ≤300 spores m−2. Category IVb missions—i.e., those carrying instruments designed to investigate extant martian life—must meet Category IVa requirements plus: “the entire landed system is restricted to a surface bioburden of ≤30 spores [note 4] or to levels of bioburden reduction driven by the nature and sensitivity of the particular life-detection system;” or “the subsystems which are involved in the acquisition, delivery, and analysis of samples used for life detection must be sterilized to these levels, and a method of preventing recontamination of the sterilized subsystem and the containment of the material to be analyzed is in place.” Category IVc missions—i.e., those accessing special regions on Mars, even if not carrying life-detection instrument—must meet Category IVa requirements plus: “if the landing site is within the special region, the entire landed system is restricted to a surface bioburden level of ≤30 spores (note 4);” or “if the special region is accessed through horizontal or vertical mobility, either the entire landed system is restricted to a surface bioburden level of ≤30 spores (note 4), or the subsystems which directly contact the special region shall be sterilized to these levels, and a method of preventing their recontamination prior to accessing the special region shall be provided.”
Note 4 The 30 spore limit “takes into account the occurrence of hardy organisms with respect to the sterilization modality. This specification assumes attainment of Category IVa surface cleanliness, followed by at least a four order-of-magnitude reduction in viable organisms. Verification of bioburden level is based on pre-sterilization bioburden assessment and knowledge of reduction factor of the sterilization modality.”

NOTE: Also shown are examples of the solar system bodies assigned to each category and the corresponding principal planetary protection requirements. Nuances of in the current planetary protection policy for Category III and IV missions to Europa and Enceladus or Category V missions to Mars, Europa, Enceladus or small solar system bodies are not shown.

SOURCE: Adapted from National Academies of Sciences, Engineering, and Medicine, Review and Assessment of Planetary Protection Policy Development Processes, The National Academies Press, Washington, D.C., 2018, p. 19, and G. Kminek, C. Conley, V. Hipkin, and H. Yano, “COSPAR Planetary Protection Policy,” Space Research Today, No. 200, pp. 12-24, December 2017.

Suggested Citation:"Appendix E: Planetary Protection Categories." National Academies of Sciences, Engineering, and Medicine. 2020. Assessment of the Report of NASA's Planetary Protection Independent Review Board. Washington, DC: The National Academies Press. doi: 10.17226/25773.
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Page73
Suggested Citation:"Appendix E: Planetary Protection Categories." National Academies of Sciences, Engineering, and Medicine. 2020. Assessment of the Report of NASA's Planetary Protection Independent Review Board. Washington, DC: The National Academies Press. doi: 10.17226/25773.
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The goal of planetary protection is to control, to the degree possible, the biological cross-contamination of planetary bodies. Guidelines developed by the Committee on Space Research (COSPAR) are used by all spacefaring nations to guide their preparations for encounters with solar system bodies. NASA's Science Mission Directorate has convened the Planetary Protection Independent Review Board (PPIRB) to consider updating the COSPAR guidelines given the growing interest from commercial and private groups in exploration and utilization of Mars and other bodies in space.

At the request of NASA, this publication reviews the findings of the PPIRB and comments on their consistency with the recommendations of the recent National Academies report Review and Assessment of the Planetary Protection Policy Development Processes.

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