As we send rovers and landers to other worlds, we have to think about the tiny microbial astronauts we’re sending along with us. In fact, NASA is so concerned about infecting other worlds that it has established the planetary protection protocols. Just to be safe.
Mars is the world we are most concerned about at this point – it has the strictest protocols. Enceladus and Europa are also being upgraded as missions are being considered and planned.
United Nations Outer Space Treaty
interplanetary contamination –Forward contamination is the transfer of viable organisms from Earth to another celestial body. Back contamination is the transfer of extraterrestrial organisms, if such exist, back to the Earth’s biosphere.
Mars 2020 mission prep