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International Agreement on Planetary Protection

UPDATED:2017年08月08日 SOURCE:本站原创

International Agreement on Planetary Protection

COSPAR Planetary Protection Activities

COSPAR has formed a Planetary Protection Panel to:

  • Develop, maintain, and promulgate planetary      protection knowledge, policy, and plans to prevent the harmful effects of      such contamination.

  • Through symposia, workshops, and topical      meetings at COSPAR Assemblies to provide an international forum for      exchange of information in this area.

  • Inform the international community, e.g.,      the Committee on the Peaceful Uses of Outer Space (COPUOS) of the United      Nations, as well as various other bilateral and multilateral      organizations, of COSPAR decisions in this area.

The details of how the policies might be carried out is important and the Space Studies Board (SSB), a branch of National Research Council (NRC), has produced a series of recommendations for specific missions.

 Recent Mars Planetary Protection Studies by the Space Studies Board

The following two studies laid the ground rules:

1992  Biological Contamination of Mars: Issues and Recommendations, which reported advice to NASA on measures to protect Mars from contamination by Earth organisms, as well as overall policy guidance.

1997  Mars Sample Return: Issues and Recommendations, which reported advice to NASA on Mars sample return missions.

 SSB Recommendations for Mars Sample Return

  • Samples returned from Mars should be      contained and treated as though potentially hazardous until proven      otherwise.

  • If sample containment cannot be verified en      route to Earth, the sample and spacecraft should either be sterilized in      space or not returned to Earth.

  • Integrity of sample containment should be      maintained through reentry and transfer to a receiving facility

  •  Controlled distribution of      unsterilized materials should only occur if analyses determine the sample      not to contain a biological hazard.

  •  Planetary protection measures adopted      for the first sample return should not be relaxed for subsequent missions      without thorough scientific review and concurrence by an appropriate      independent body.

  • Avoiding contamination of returned samples      with organisms or organic material of terrestrial origin:  “It will      be important to stringently avoid the possibility that terrestrial      organisms, their remains, or organic matter in general could inadvertently      be incorporated into sample material returned from Mars.       Contamination with terrestrial material would compromise the integrity of      the sample by adding confusing background to potential discoveries related      to extinct or extant life on Mars….  Because the detection of life or      evidence of pre biotic chemistry is a key objective of Mars exploration,      considerable effort to avoid such contamination is justified.”

  • In-flight sterilization.

Sample handling and preservation

Two issues were considered important:

  • Ensuring sample containment

  • Avoiding return of uncontained martian      material

Planetary Protection Requirements for Sample Return (1)

Sterilization of outbound spacecraft (Category IV-B)

  • Concern is that terrestrial contamination      of the returned sample may precipitate “false positive” in the search for      evidence of extraterrestrial life, or in the hazard determination      protocol.

  • Departures from sterilization requirement      must be justified by thorough modeling and/or experimentation.

Clean/sterilize spacecraft surfaces that will come into contact with sample, and keep them clean

  • Prevention of      recontamination/cross-contamination is the hard part.

  • If contamination cannot be avoided, it      needs to be extensively characterized.

  • An inability to unequivocally identify a      viable entity in the sample as Earth-life may mean that an unsterilized      sample can never be released from containment.

Planetary Protection Requirements for Sample Return (2)

Sealed Extraterrestrial sample container

  • Prevent accidental release into Earth’s      environment (the technical challenge may be to confirm that the sample is      sealed).

Design multiple means for sealing the container (multiple layers)

  • Provide for fail-safe maintenance of seal      in various Earth-landing modes.

  • Provide for initial verification that      design performed sealing action, and verify only anomalous indications and      non-nominal situations.

  • If verification of seal and completion of      nominal operations cannot be demonstrated, then Earth return must be      abandoned.

Planetary Protection Requirements for Sample Return (3)

  •  Break the chain of contact with the      planetary body:

    • Preclude any       “hitchhiker” entities traveling with the returned vehicle (and not       contained within the sealed sample container).

  • Design for Mars isolation in sample      canister loading, launch, and transfer operations:

    • Avoid       recontamination during sample-transfer operations subsequent to Mars       Return Vehicle launch.

    • Provide additional       containment of sample canister within Earth Return Vehicle.

Planetary Protection Requirements for Sample Return (4)

Quarantine and testing

  • Contain unsterilized samples until required      “biohazard” testing is completed.

  • Conduct initial characterization of      returned samples and allocate portion for biohazard determination.

  • Allocate sterilized samples for special      testing prior to distribution of unsterilized sample portion (may be      necessary for completion of biohazard testing, as well).

  • Avoid Earth contamination of the sample throughout      sample receiving, initial characterization, biohazard testing, and      subsequent curation and distribution.

 Current Mars Planetary Protection Study by the Space Studies Board

  • Certification and Curation of Martian      Samples.

  • Committee on Planetary and Lunar      Exploration.

Requirements for a quarantine and biosafety certification facility for extraterrestrial samples, with the central question:

  • What are the criteria that must be      satisfied before samples can be released from the quarantine facility?

Closely related issues include:

  • What are the optimal techniques for      isolating and handling planetary materials, determining their content of      biota (if any), and carrying out basic geochemical characterization      studies in the certification facility?

  • How much capability for scientific analysis      beyond that required for biosafety certification should be incorporated      into the facility, and what principles should govern the utilization of      this scientific capability?

  • To what extent can valuable lessons be      learned from the Apollo quarantine experience?


In addition to Mars, a mission to the Jupiter moon, Europa, is planned and attention is now being paid as to its protection from contamination.

NRC Study: Preventing the Forward Contamination of Europa

The NRC Space Studies Board task group is evaluating the planetary protection requirements and methods used to prevent forward contamination of Europa in future orbiter and lander missions and will recommend any necessary changes. Specifically, they will:

  • assess the levels of cleanliness and      sterilization required to prevent forward contamination of Europa given      Europa's unique environment and our current understanding of terrestrial      microorganisms;

  • review methods used to achieve the      appropriate level of cleanliness and sterilization of spacecraft and      recommend alternatives in light of recent advances in science and      technology; and,

  • identify scientific investigations that      should be accomplished to reduce the uncertainty in the above assessment.

 Europa Orbiter Science Objectives

Group 1 Objectives:

  • Determine the presence or absence of a      subsurface ocean;

  • Characterize the three-dimensional      distribution of any subsurface liquid water and its overlying ice layers;      and,

  • Understand the formation of surface      features, including sites of recent or current activity, and identify      candidate landing sites for future lander missions.

Group 2 Objectives:

  • Characterize the surface composition,      especially compounds of interest to pre biotic chemistry;

  • Map the distribution of important constituents      on the surface; and

  • Characterize the radiation environment in      order to reduce the uncertainty for future missions, especially landers.

  Recommendations: NRC Report on Small Body Sample-Return

All samples returned from planetary satellites and small solar system bodies that must be contained should be treated as potentially hazardous until proven otherwise.

No sample containment and handling is warranted beyond what is needed for scientific purposes for:

  • Moon, Io, new comets, Interstellar Dust      Particles (IDP)* with a High Degree of Confidence

  • Phobos, Deimos, Callisto, C-type asteroids,      undifferentiated metamorphosed asteroids, differentiated asteroids, all      other comets, IDP’s* with a Lesser Degree of Confidence

  • Strict containment and handling are      warranted for:

  • Europa, Ganymede, P-type asteroids, D-type      asteroids, IDP’s*

  • Sample return provisions for contained      samples are the same as for Mars

  *Depending on parent body and time of exposure to space environment

Planetary protection measures adopted for the first sample return should not be relaxed for subsequent missions without thorough scientific review and concurrence by an appropriate independent body.  For samples returned from bodies where a Lesser Degree of Confidence is indicated for containment and handling, a conservative, case-by-case approach should be used to assess the containment and handling requirements

NASA should consult with or establish an advisory committee with expertise in the planetary and biological sciences relevant to such an assessment

NASA should consult with or establish an advisory committee of experts from the scientific community when developing protocols and methods to examine returned samples for indicators of past or present extraterrestrial life forms


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