posted on May, 19 2003 @ 06:11 PM
I seriously doubt there is much in the way of a credible concern here. Look at it like this:
On any sample return mission, the sample is going to be encapsulated inside an airtight container inside the spacecraft (they dont want to contaminate
it with earth air). Any material stuck on the outside of the spacecraft is going to be sterilized during reentry as the temperatures reach several
thousands of degrees.
So, unless someone actively steals the sample, opens it, and spreads it into the jet stream (and then, and only then, if there is something that likes
the earth biosphere and can survive) would there be a possibility of an infection problem.
Also, consider that a totally alien bacteria, especially one that would have evolved on Mars (which is a CO2, anaerobic atmosphere), would be totally
incapable of surviving in our O2 atmosphere.