Mark says: I'm quite sure that humans will be needed even if life is found
robotically to comprehensively study it. Robotic collection and return to a
manned Martian lab is a relatively simple solution to your contamination
concern.

Regards,
Mark

My reply:

http://www.icamsr.org/petition.html

Phase 1) Increase the number of life sciences landers going to Mars and land them in different geographical locations. These landers will carry out in-situ testing of the Martian surface/subsurface to narrow the probability range of any life detected in the samples; a) define the environmental envelope for growth and survival of any life detected. Also, this phase would also test inhibitory agents for effectiveness on any life found.

Phase 2) A second series of tests will be conducted in Martian orbit aboard a newly designed automated life sciences laboratory for the purpose to determine any interactions between Martian microorganisms and selected terrestrial ecosystems.

Phase 3) After numerous robotic spacecraft have conducted their life sciences survey of the surface of Mars in many different locations, the cautious return of samples to the vicinity of the Earth may proceed. Upon achieving Earth orbit, the Mars Sample canister status would be evaluated by a qualified Biohazard Reentry Team aboard a vehicle like SpaceHab or the International Space Station. Preliminary quarantine tests would be conducted in Earth orbit before transfer to the Earth's surface.

Phase 4) Once phases 1-3 have been carried out, the Mars Sample Return canister with samples inside would be transferred to the Earth's surface to be analyzed in a high security Level 4 Planetary Sample receiving Laboratory.