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One thing I wonder about is if we go to Mars and find microbial life at some later point. Will we ever be able to be sure that the microbes were there before us

by CoryG89 10y ago

One thing I wonder about is if we go to Mars and find microbial life at some later point. Will we ever be able to be sure that the microbes were there before us, or did we bring them with us without realizing, after which they reproduced until we detected them?

maze-le 10y ago
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
fractalwrench 10y ago
If we contaminated Mars with microbial life from Earth, it would have a similar genetic signature to sequenced organisms on Earth. Assuming we could get a DNA sequencing machine up there, it would probably be obvious that the organism originated from Earth unless it was some previously undiscovered Archaea.
- CoryG89 10y ago
  Sure, assuming that we find life that is significantly different than life on Earth. If all we find is microbial life that is genetically similar to that on Earth, then you might be inclined to believe we brought it there, but it seems possible there might be no way to know for sure.

by CoryG89 10y ago

maze-le 10y ago

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

fractalwrench 10y ago

If we contaminated Mars with microbial life from Earth, it would have a similar genetic signature to sequenced organisms on Earth. Assuming we could get a DNA sequencing machine up there, it would probably be obvious that the organism originated from Earth unless it was some previously undiscovered Archaea.

CoryG89 10y ago
Sure, assuming that we find life that is significantly different than life on Earth. If all we find is microbial life that is genetically similar to that on Earth, then you might be inclined to believe we brought it there, but it seems possible there might be no way to know for sure.