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Worry of the month: Could humans have contaminated Mars with life?

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Clean rooms could be making microbes hardier, says molecular and genetic space flight expert:

Spacecraft are built rooms with air filters and strict biological control procedures. These are designed to ensure that only a few hundred particles can contaminate each square foot and ideally no more than a few dozen spores per square metre.

But, it is almost impossible to get to zero biomass on a spacecraft. Microbes have been on Earth for billions of years, and they are everywhere. They are inside us, on our bodies, and all around us. Some can sneak through even the cleanest of clean rooms…

In JPL’s clean rooms, we found evidence of microbes that have the potential to be problematic during space missions. These organisms have increased numbers of genes for DNA repair, giving them greater resistance against radiation, they can form biofilms on surfaces and equipment, can survive desiccation and thrive in cold environments. It turns out that clean rooms might serve as an evolutionary selection process for the hardiest bugs that then may have a greater chance of surviving a journey to Mars…

There is a chance, however, that if we do detect signs of life on Mars, it could have come from Earth in the first place. Ever since the first two Soviet probes landed on the Martian surface in 1971, followed by the US Viking 1 lander in 1976, there likely have been some fragments of microbial, and maybe human DNA, on the Red Planet. Given the global dust storms and trace amounts of DNA that might have gone with these spacecraft, we have to be sure we don’t fool ourselves that the life we find isn’t originally from Earth.

Christopher Mason, “Could humans have contaminated Mars with life?” at BBC (May 10, 2021)

But wait. If life got started very early, while Earth and Mars were still exchanging fragments, it’s possible some hardy life forms were from Earth anyway, no? Better yet, maybe we will find out that some Earth life forms were originally from Mars.

Hey, the Uncommon Descent News Virtual Coffee Room has always maintained that the Martians have been among us since forever but they don’t make a lot of noise …

China lands Rover on Mars to look for water, life National Geographic: Utopia Planitia, thought to be the site of an ancient sea, has sedimentary layers that could contain evidence of past water. Even more exciting, these layers of rock could contain traces of any past life on Mars, says James Head III, a planetary scientist at Brown University.

Molecular weight O2 - 32 H2O- 17 CO2 - 44 Is it correct to assume that Mars will have an almost impossible time accumulating water on its surface or in its atmosphere because of its relatively small mass and the low molecular weight of water? jerry
Bob O'H Interesting - did not know that. I was actually referring to the density of the atmosphere more than the composition, but even at 100x thinner, 95% CO2 is probably significant. I stand corrected. drc466
Drc466 - little or no CO2 on mars? Apparently the atmosphere is almost 95% CO2. Bob O'H
So, I'm no biologist, but going down the checklist of things in the "little to no" column on Mars: Oxygen Water Carbon Dioxide Photosynthesis Glucose Stable Temperatures UV Protection I'm going to hazard a guess that anything older than a few centuries has degraded, and anything sent from earth is either dead or in extreme hibernation. So unless we drop search bots directly on top of the previous bots... drc466
The interesting part is that spaceflight helped us to realize the infinite flexibility of bacteria. Not from what we saw on other planets, but from what we saw on our spaceships in orbit. The accidental experiments on the skin of ISS gained more knowledge than the intentional experiments conducted inside ISS. polistra

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