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Historical Origins of Planetary Protection Policies

The international community expressed concern about space exploration possibly contaminating planetary bodies, jeopardizing their biological exploration, and posing risks to the Earth’s biosphere even before Sputnik began the spaceflight era. In 1956, the International Astronautical Federation attempted to coordinate international efforts to prevent interplanetary contamination, and, 2-years later, the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) made initial attempts to deal with interplanetary contamination and spacecraft sterilization. In 1957, the U.S. National Academy of Sciences (NAS) urged that lunar and planetary studies avoid interplanetary contamination and asked the International Council for Science¹ (ICSU) to assist evaluating the possibilities of such contamination and developing means to prevent it. In 1958, the NAS established the Space Science Board (SSB),² which, among other duties, was charged with developing advice on interplanetary contamination. Thus, the SSB and the expert committees it oversees played a major role in studying planetary protection issues, making recommendations on planetary protection questions posed by NASA, and establishing U.S. planetary protection policies.

Also in 1958, ICSU established an ad hoc Committee on Contamination by Extraterrestrial Exploration (CETEX). CETEX recommended establishing a code of conduct for space missions and research. In accepting the CETEX recommendations, ICSU established the Committee on Space Research (COSPAR) to coordinate worldwide space research. In 1961, ICSU declared that all countries launching space experiments that could have an adverse effect on other scientific research should provide ICSU and COSPAR with the information necessary to evaluate the potential contamination.³ In 1962, COSPAR organized a Consultative Group on Potentially Harmful Effects of Space Experiments to help conduct these evaluations. These actions set the foundations for the key role COSPAR has played in the international development of planetary protection policies. Inputs from national organizations, such as the SSB, inform COSPAR’s deliberative processes that establish consensus planetary protection policies.

In 1963, on the basis of SSB studies and advice, NASA adopted planetary protection policies for the Moon, Mars, and Venus. COSPAR followed suit in 1964 and established an interim quantitative framework for developing planetary protection standards that set limits on the probabilities of carrying viable organisms aboard spacecraft to planetary bodies or producing accidental impacts. COSPAR replaced this interim framework in 1967 with a policy that guided planetary protection measures until 1983. This new policy prescribed limits on the probability that a planet would be contaminated during the so-called period of biological exploration.

In 1982, acting on the SSB’s advice, NASA revised its planetary protection policy to establish requirements for target planet and mission type combinations (i.e., orbiter, lander, etc.) and to consider sample-return missions as a separate category. The revised policy also imposed implementing procedures

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¹ Then known as the International Council of Scientific Unions.

² In 1989 the Space Science Board expanded its disciplinary responsibilities and changed its name to the Space Studies Board.

³ For more information on the role of the Committee on Space Research (COSPAR) see, for example, COSPAR, “Panel on Planetary Protection (PPP),” last update October 2, 2015, https://cosparhq.cnes.fr/scientificstructure/ppp.

to ensure that planet-mission combinations warrant specific planetary protection controls (e.g., trajectory biasing, cleanroom assembly, spacecraft bioload reduction, etc.). Following continuing SSB advice, COSPAR revised its comprehensive policy in 2011. That policy, which remains in effect today, states the following:

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⁴ G. Kminek and J.D. Rummel, “COSPAR’s Planetary Protection Policy,” Space Research Today 193, August 2015, pp. 7-19.