Human missions to Mars raise planetary-protection challenges

The rationale given for Mars missions over the past 20 years has been the search for life. Sending humans there to live would be a major philosophical departure; the prospect was also described as exciting and somewhat inevitable.

Space law is considered underdeveloped, and private space activity is putting pressure on the system. A provision in the 1970 Outer Space Treaty against harmful contamination is now interpreted to include preventing Earth life from reaching places that might host life. COSPAR and other organizations are working on how to assess risks for a first human mission, since people and their microbiomes cannot be sterilized like robotic missions.

A published paper proposes a framework for gathering data to assess whether organisms intended for Mars could become invasive. A biomanufacturing organism was described as well characterized and likely to die quickly outside its bioreactor, but applying the same assessment to humans and their microbiomes remains unclear. Martian life was described as unlikely, but the risk of interfering with it remains a concern.