Human missions will inevitably introduce considerations that go beyond those covered by the forward contamination controls and policies discussed in this report. Furthermore, they are likely to involve examination of COSPAR policies and questions about minimizing potential contamination that could be introduced through human operations, exploration, construction, sampling, and sequencing of activities. Today, there are no official COSPAR or NASA policies encompassing forward contamination of solar system bodies during human missions. Although significant study will be necessary before planning and implementing contamination controls for human missions, the committee recognizes that planetary protection considerations will be important in all phases of future missions, whether robotic or human. The committee notes that previous NRC reports—Biological Contamination of Mars: Issues and Recommendations (NRC, 1992) and Safe on Mars: Precursor Measurements Necessary to Support Human Operations on the Martian Surface (NRC, 2002)—have addressed human missions to Mars and have concluded that information from precursor robotic missions is critical for planning safe, productive human missions that will have a minimal impact on Mars.

In anticipating the long-term potential for expansion of human activities on Mars, it may be prudent to consider forward contamination policies in the context of analogous policies for sensitive environments on Earth, such as the international treaty governing Antarctica.11 Like the Outer Space Treaty, the Antarctic Treaty calls for peaceful use for humanity, freedom of scientific investigations, and international cooperation. The Antarctic Treaty also specifically calls for the preservation and conservation of living resources in Antarctica. Examination of the administrative oversight and controls imposed on research and activities in polar areas, such as the designation of special regions, requirements for waste disposal and cleanup, and reversibility of human actions, may be useful in developing a framework for addressing concerns related to forward contamination by human missions.

The committee does not, however, take a position on whether human missions to Mars will or will not necessarily broadly contaminate the martian surface with terrestrial microorganisms—a topic that will require extensive study and possibly research and development (R&D).

Implementation of Planetary Protection

Translating planetary protection into actual practice involves a complex mix of intertwined policies, elements of science and engineering, uncertainties, and implementation protocols. For past robotic missions to Mars, forward contamination controls have included the requirement to reduce the biological contamination of the spacecraft, constraints on spacecraft operating procedures, and inventories of organic constituents of the spacecraft and organic samples, along with documentation of spacecraft operations, impact potential, and the location of landing or impact points on the planetary surface.

Upon request, the SSB has provided advice to NASA about planetary protection (see Appendix B). In 1978, the SSB produced Recommendations on Quarantine Policy for Mars, Jupiter, Saturn, Uranus, Neptune, and Titan, which considered planetary protection for several bodies (NRC, 1978). In 1992, the SSB issued Biological Contamination of Mars: Issues and Recommendations (NRC, 1992), while other reports have considered sample return and back contamination. SSB reports have provided scientific input that has been used to update COSPAR policies as well as practices that must be implemented to meet those policies.

COSPAR maintains and issues policy guidance on planetary protection to the international space science community. NASA and other national space agencies adhere to COSPAR planetary protection policy to avoid the contamination of extraterrestrial bodies. NASA’s Planetary Protection Office provides the implementation requirements for planetary protection for NASA’s planetary exploration program, including the Mars Exploration Program. The methods and practices of planetary protection developed during the 1970s for the Viking mission set the standard operating procedures that are still in use today. Current planetary protection practices and their historical development are discussed in detail in Chapter 2. Important terminology in the planetary protection lexicon is defined in Box 1.1.


The Antarctic Treaty, December 1, 1959. For text, see Rauf et al. (2000), pp. 132-135. For a historical account of the treaty, see NRC (1993).

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement