Mike F. wrote:
Drilling into ancient ice or geological strata on Earth can be just as dangerous as bringing back a piece of Mars.

What if a virulent, long-lived bacteria or virus died out in an area for lack of hosts and was later covered with ice or sediment?

Alex writes:
A good example is the particular strain for Spanish influenza (from the 1918 pandemic), remnants of which can still be extracted from corpses buried in arctic environments. Furthermore, viral life forms can spend lengthy times hiding in protected environs and then burst forth for no apparent reason. Recall the Ebola virus. There are two strains, Ebola Zaire and Ebola Sudan, one lethal to humans, the other lethal to apes. This is why Zubrin's "Dutch Elm disease" analogy is faulty; microbes can and do mutate and jump species. However, prudent precautions (such as BSL-4 facilities, expert handling, etc.) can mitigate the risk to manageable proportions, which is why DiGregorio's alarmist fears are unfounded.

Alex R. Blackwell
University of Hawaii