Historically, planetary protection policy has addressed the concern that the forward contamination of planetary environments by terrestrial organisms could compromise spacecraft investigations sent to identify indigenous life.2 As a result, current practice imposes the strictest standards of cleanliness on those spacecraft that will conduct life-detection experiments. Other spacecraft that will not search for life are required to meet less stringent standards.

Although this policy may succeed in protecting the integrity of Mars mission science during the near-term period of biological exploration, recent discoveries suggest that there may be numerous (and potentially difficult to detect) environments on Mars where the probability of growth for terrestrial organisms is substantially higher than previously thought. If so, there is the potential that the lower standard of cleanliness afforded for spacecraft that do not include life-detection experiments may allow the introduction of terrestrial organisms into sensitive environments where they may reproduce.

The ethical and policy implications of questions about protection of the planet Mars are not currently addressed by either the Outer Space Treaty or COSPAR policies. Although they fall outside the mandate of the current committee, the committee believes that their consideration should have high priority. The need for urgency in deliberations on protection of the planet Mars as well as protection of science is underscored by the present uncertainty about the distribution of such sensitive martian environments, the failure rate and cleanliness levels of Mars landers, and the projected rapid pace of future spacecraft investigations (see Box 8.1). For these reasons, the committee believes that it is important that NASA and its international partners address questions about the protection of the planet Mars as expeditiously as possible.

Recommendation 1. In light of new knowledge about Mars and the diversity and survivability of terrestrial microorganisms in extreme environments, NASA should work with COSPAR and other appropriate organizations to convene, at the earliest opportunity, an international workshop to consider whether planetary protection policies for Mars should be extended beyond protecting the science to include protecting the planet. This workshop should focus explicitly on (1) ethical implications and the responsibility to explore Mars in a manner that minimizes the harmful impacts of those activities on potential indigenous biospheres (whether suspected or known to be extant), (2) whether revisions to current planetary protection policies are necessary to address this concern, and (3) how to involve the public in such a dialogue about the ethical aspects of planetary protection.


Many existing planetary protection practices stem from the R&D on planetary protection that was conducted during the 1970s in preparation for sending the Viking life-detection missions to Mars. Since that time, knowledge about Earth organisms and their ability to survive under severe conditions has advanced considerably, and the potential presence of such organisms on spacecraft may warrant alternative approaches to reducing bioburden. Over the last 30 years as well, new technologies for assessing microbial diversity and reducing bioburden on spacecraft have been developed. If applied properly, they should allow researchers, engineers, and planetary protection officials to improve both microbial detection and bioburden reduction methods compared to those currently being used (see Chapter 6). Transitioning NASA’s planetary protection practices so that they reflect current scientific understanding of Mars and microbiology and also benefit from the use of advanced technologies will require investing in a series of R&D efforts on and assessments of new technologies that can be applied to the implementation of planetary protection policies. It will also require a structure for managing such research efforts in coordination with the engineering, spacecraft and instrument development, and science communities at NASA


This position originated in the decade before the promulgation of the Outer Space Treaty of 1967 (see Chapter 1).

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