With regard to recent claims that Zubrin is utterly wrong with regard to planetary protection issues.

From the NRC report at http://www.nas.edu/ssb/mrsrexec.html

"Because pathogenesis requires specific adaptations to overcome the extensive defenses possessed by all Earth organisms, virulent extraterrestrial pathogens are unlikely. Subcellular disease agents, such as viruses and prions, are biologically part of their host organisms, and so an extraterrestrial source is extremely unlikely. Conceivably, putative extraterrestrial organisms could be capable of opportunistic infections or toxicity, as are some terrestrial bacteria, but such a risk can be eliminated by standard laboratory control procedures."

The coevolutionary comments sound indistinguishable from Zubrin's to me. The issues of toxicity and opportunistic infections have not been addressed by Zubrin as far as I know which does count as a significant oversite in my view and that of many others. However, as Zubrin mentioned in his Planetary Report followup none of the PP experts addressed the issue of why containment should be required in the face of evidence for interplanetary exchange of meteorites. I would be most interested to hear from Keith how he and all the other PP experts he knows feel about both the likelyhood of transferring life uncontrolled by impacts and whether there is any way to assess whether any of the risks mentioned occurred in the past due to such exchanges.

Regards,
Mark