Responding to concerns raised in the scientific community that spaceflight missions to the Moon and other celestial bodies might compromise their future scientific exploration, in 1958 the International Council of Scientific Unions (ICSU) established an ad-hoc Committee on Contamination by Extraterrestrial Exploration (CETEX) to provide advice on these issues. In the next year, this mandate was transferred to the newly founded Committee on Space Research (COSPAR), which as an interdisciplinary scientific committee of the ICSU (now the International Council for Science) was considered to be the appropriate place to continue the work of CETEX. Since that time, COSPAR has provided an international forum to discuss such matters under the terms “planetary quarantine” and later “planetary protection”, and has formulated a COSPAR Planetary Protection Policy with associated implementation requirements as an international standard to protect against interplanetary biological and organic contamination, and after 1967 as a guide to compliance with Article IX of the UN Space Treaty in that area (see for reference: UNOOSA 2017, Report of the Committee on the Peaceful Use of Outer Space, 60th Session, A/72/20, United Nations, New York).
Updating the COSPAR Planetary Protection Policy, either as a response to new discoveries or based on specific requests, is a process that involves representatives from the COSPAR Scientific Commissions B (Space Studies of the Earth-Moon System, Planets, and Small Bodies of the Solar System) and F (Life Sciences as Related to Space), national and international scientific organizations and unions and individual scientists (Figure 1). After reaching a consensus among the involved parties, the proposed update is formulated by the COSPAR Panel on Planetary Protection and submitted to the COSPAR Bureau and Council for review and approval. 13 The COSPAR Planetary Protection Policy described in this paper is the currently approved version (dated March 2017) and based on the COSPAR Panel on Planetary Protection Colloquium (published in Space Research Today, #195, April 2016) and the COSPAR Panel on Planetary Protection Business Meeting (2 August 2016). Updates affect only some requirements for Mars (Mars Special Regions) and for Enceladus (new requirements) with respect to the previous version of the policy published in Space Research Today, #193, August 2015.
Noting that COSPAR has concerned itself with questions of biological contamination and spaceflight since its very inception, and
noting that Article IX of the Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies (also known as the UN Space Treaty of 1967) states that : “States Parties to the Treaty shall pursue studies of outer space, including the Moon and other celestial bodies, and conduct exploration of them so as to avoid their harmful
contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter, and where necessary, shall adopt appropriate measures for this purpose.”
therefore, COSPAR maintains and promulgates this planetary protection policy for the reference of spacefaring nations, both as an international standard on procedures to avoid organic-constituent and biological contamination in space exploration, and to provide accepted guidelines in this area to guide compliance with the wording of this UN Space Treaty and other relevant international agreements.
Referring to COSPAR Resolutions 26.5 and 26.7 of 1964 , the Report of the Consultative Group on Potentially Harmful Effects of Space Experiments of 1966, the Report of the same Group of 1967, and the Report of the COSPAR/IAU Workshop of 2002 ,
notes with appreciation and interest the extensive work done by the Panel on Standards for Space probe Sterilization and its successors the Panel on Planetary Quarantine and the Panel on Planetary Protection and
accepts that for certain space mission/target body combinations, controls on contamination shall be imposed in accordance with a specified range of requirements, based on the following policy statement:
The conduct of scientific investigations of possible extraterrestrial life forms, precursors, and remnants must not be jeopardized. In addition, the Earth must be protected from the potential hazard posed by extraterrestrial matter carried by a spacecraft returning from an interplanetary mission. Therefore, for certain space mission/target planet combinations, controls on contamination shall be imposed in accordance with issuances implementing this policy. ([4, 5]; ESA PPWG 2008)
The five categories for target body/mission type combinations and their respective suggested ranges of requirements are described as follows, and in Table 1. Assignment of categories for specific mission/body combinations is to be determined by the best multidisciplinary scientific advice. For new determinations not covered by this policy, such advice should be obtained through the auspices of the Member National Scientific Institutions of COSPAR. In case such advice is not available, COSPAR will consider providing such advice through an ad hoc multidisciplinary committee formed in consultation with its Member National Scientific Institutions and International Scientific Unions:
Category I includes any mission to a target body which is not of direct interest for understanding the process of chemical 14 evolution or the origin of life. No protection of such bodies is warranted and no planetary protection requirements are imposed by this policy.
Category II missions comprise all types of missions to those target bodies where there is significant interest relative to the process of chemical evolution and the origin of life, but where there is only a remote2 chance that contamination carried by a spacecraft could compromise future investigations. The requirements are for simple documentation only. Preparation of a short planetary protection plan is required for these flight projects primarily to outline intended or potential impact targets, brief Pre- and Post-launch analyses detailing impact strategies, and a Post-encounter and End-of-Mission Report which
2 “Remote” here implies the absence of environments where terrestrial organisms could survive and replicate, or a very low likelihood of transfer to environments where terrestrial organisms could survive and replicate.
will provide the location of impact if such an event occurs. Solar system bodies considered to be classified as Category II are listed in the Appendix to this document.
Category III missions comprise certain types of missions (mostly flyby and orbiter) to a target body of chemical evolution and/or origin of life interest and for which scientific opinion provides a significant3 chance of contamination which could compromise future investigations. Requirements will consist of documentation (more involved than Category II) and some implementing procedures, including trajectory biasing, the use of cleanrooms during spacecraft assembly and testing, and possibly bioburden reduction. Although no impact is intended for Category III missions, an inventory of bulk constituent organics is required if the probability of impact is significant. Category III specifications for selected solar system bodies are set forth in the Appendix to this document. Solar system bodies considered to be classified as Category III also are listed in the Appendix.
Category IV missions comprise certain types of missions (mostly probe and lander) to a target body of chemical evolution and/or origin of life interest and for which scientific opinion provides a significant2 chance of contamination which could compromise future investigations. Requirements imposed include rather detailed documentation (more involved than Category III), including a bioassay to enumerate the bioburden, a probability of contamination analysis, an inventory of the bulk constituent organics and an increased number of implementing procedures. The implementing procedures required may include trajectory biasing, cleanrooms, bioburden reduction, possible partial sterilization of the direct contact hardware and a bioshield for that hardware. Generally, the requirements and compliance are similar to Viking, with the exception of complete lander/probe sterilization. Category IV specifications for selected solar system bodies are set forth in the Appendix to this document. Solar system bodies considered to be classified as Category IV also are listed in the Appendix.
Category V missions comprise all Earth-return missions. The concern for these missions is the protection of the terrestrial system, the Earth and the Moon. (The Moon must be protected from back contamination to retain freedom from planetary protection requirements on Earth-Moon travel.) For solar system bodies deemed by scientific opinion to have no indigenous life forms, a subcategory “unrestricted Earth return” is defined. Missions in this subcategory have planetary protection requirements on the outbound phase only, corresponding to the category of that phase (typically Category I or II). For all other Category V missions, in a subcategory defined as “restricted Earth return,” the highest degree of concern is expressed by the absolute prohibition of destructive impact upon return, the need for containment throughout the return phase of all returned hardware which directly contacted the target body or unsterilized material from the body, and the need for containment of any unsterilized sample collected and returned to Earth. Post-mission, there is a need to conduct timely analyses of any unsterilized sample collected and returned to Earth, under strict containment, and using the most sensitive techniques. If any sign of the existence of a nonterrestrial replicating entity is found, the returned sample must remain contained unless treated by an effective sterilizing procedure. Category V concerns are reflected in requirements that encompass those of Category IV plus a continuing monitoring of project activities, studies and research (i.e., in sterilization procedures and containment techniques).
Recommends that COSPAR members inform COSPAR when establishing planetary protection requirements for planetary missions, and
3 “Significant” here implies the presence of environments where terrestrial organisms could survive and replicate, and some likelihood of transfer to those places by a plausible mechanism.
Recommends that COSPAR members provide information to COSPAR within a reasonable time not to exceed six months after launch about the procedures and computations used for planetary protection for each flight and again within one year after the end of a solar system exploration mission about the areas of the target(s) which may have been subject to contamination. COSPAR will maintain a repository of these reports, make them available to the public, and annually deliver a record of these reports to the Secretary General of the United Nations. For multinational missions, it is suggested that the lead partner should take the lead in submitting these reports.
- The estimated bioburden at launch, the methods used to obtain the estimate (e.g., assay techniques applied to spacecraft or a proxy), and the statistical uncertainty in the estimate.
- The probable composition (identification) of the bioburden for Category IV missions, and for Category V “restricted Earth return” missions.
- Methods used to control the bioburden, decontaminate and/or sterilize the space flight hardware.
- The organic inventory of all impacting or landed spacecraft or spacecraft-components, for quantities exceeding 1 kg.
- Intended minimum distance from the surface of the target body for launched components, for those vehicles not intended to land on the body.
- Approximate orbital parameters, expected or realized, for any vehicle which is intended to be placed in orbit around a solar system body.
- For the end-of-mission, the disposition of the spacecraft and all of its major components, either in space or for landed components by position (or estimated position) on a planetary surface.
IMPLEMENTATION GUIDELINES AND CATEGORY SPECIFICATIONS FOR INDIVIDUAL TARGET BODIES
Guidelines on the Implementation of an Organic Inventory
A spacecraft organic inventory includes a listing of all organic materials carried by a spacecraft which are present in a total mass greater than 1 kg. A complete inventory should include organic products that may be released into the environment of the protected solar system body by propulsion and life support systems (if present), and include a quantitative and qualitative description of major chemical constituents and the integrated quantity of minor chemical constituents present.
Category-Specific Listing of Target Body/Mission Types
Category I: Flyby, Orbiter, Lander: Undifferentiated, metamorphosed asteroids; Io; others to-be-defined (TBD)
Category II: Flyby, Orbiter, Lander: Venus; Moon (with organic inventory); Comets; Carbonaceous Chondrite Asteroids; Jupiter; Saturn; Uranus; Neptune; Ganymede*; Callisto; Titan*; Triton*; Pluto/Charon*; Ceres; KuiperBelt Objects > 1/2 the size of Pluto*; KuiperBelt Objects < 1/2 the size of Pluto; others TBD
Category III: Flyby, Orbiters: Mars; Europa; Enceladus; others TBD
Category IV: Lander Missions: Mars; Europa; Enceladus; others TBD
Category V: Any Earth-return mission
“Restricted Earth return”: Mars; Europa; others TBD
“Unrestricted Earth return”: Venus, Moon; others TBD
*The mission-specific assignment of these bodies to Category II must be supported by an analysis of the “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 x 10-4), addressing both the existence of such environments and the prospects of accessing them.
NOTE: The main body text is replicated here in its entirety without figures. Only appendices to the COSPAR Planetary Protection Policy relevant to lunar missions are included here. The full text is available at https://cosparhq.cnes.fr/assets/uploads/2020/07/PPPolicyJune-2020_Intro_Web.pdf.