A proposed new policy for planetary protection

A policy on the protection of extraterrestrial bodies from contamination by terrestrial microorganisms and organic constituents that might interfere with studies of chemical and biological evolution on those bodies is proposed which is based on new information gained in planetary exploration over the past decade. The proposed policy overcomes the difficulties associated with the uncertainties in parameters and the rigid requirements of the current probabilistic approach by eliminating the general quantitative guideline and by calling for the implementation of planetary protection procedures for space projects by exception, depending on target planet and type of encounter. The impact of the proposed policy on the implementation of future space missions is illustrated for the Galileo Jupiter mission, a cometary mission, the Saturn Orbiter with Twin Probes, and a Mars Surface Sample Return Mission, and procedures which may lead to the eventual adoption of the policy are noted.