TABLE 7.1 Comparison of Major Recommendations Made in Previous Reports from the National Research Council, NASA, and the iMARS Working Group


Approaches Recommended

NRC 1997a

NRC 2002b

Planetary Protection Overall and En Route (Inbound to SRF)


No uncontained martian materials may be returned to Earth unless sterilized

Not applicable; (study only considers the handling of materials on Earth)

If containment not verified en route, must sterilize or not return to Earth

Not discussed

Containment integrity maintained throughout re-entry and transfer to SRF

Not discussed; report focuses on samples after arrival at SRF

Planetary Protection Measures (Missions)

Planetary protection controls should not be relaxed for future missions without review by an independent scientific body

Not applicable

Assumptions About Martian Life

Extraterrestrial Life

Martian life might exist and could be returned in samples, but martian organisms unlikely to pose a risk of pathogenic or ecological effects on Earth

Possibility that samples from Mars will contain viable martian microorganisms—which requires that samples be handled in ways that will protect both terrestrial environments and martian samples from any cross-contamination


Samples should be contained and treated as potentially hazardous until proven otherwise; potential biohazards viewed as replicating entities; martian life deemed unlikely to cause infectious, pathogenic, or ecological effects, although the probability is not zero. Subcellular disease agents (e.g., viruses, prions) are biologically part of their host organisms, and extraterrestrial sources of such agents that could affect Earth organisms are extremely unlikely

Agrees with the need to contain and test samples before release; raises concerns that returned samples could include replicating organisms that are self-reliant and able to proliferate in an alien terrestrial world (ignores the potential for viruses, viroids, prions, or other possible biohazards)

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