The concepts you are referring to are called: Interplanetary contamination[0] and Planetary Protection[1]. There are precautions that take place before a spacec

The concepts you are referring to are called: Interplanetary contamination[0] and Planetary Protection[1]. There are precautions that take place before a spacecraft, targeted at possible sources of microbial life is launched. The operations vehicles are basically sterilized beforehand. >> "The aim of the current regulations is to keep the number of microorganisms low enough so that the probability of contamination of Mars is acceptable" Contamination can happen both ways. Not only on the way to the planet but also on the way back, if a sample-return is involved. The sample must be kept sterile on the way back to earth, to the lab, and in the lab without destroying information by sterilizing it again... [0]: https://en.wikipedia.org/wiki/Interplanetary_contamination https://en.wikipedia.org/wiki/Interplanetary_contamination [1]: https://en.wikipedia.org/wiki/Planetary_protection https://en.wikipedia.org/wiki/Planetary_protection