Eli5: If creatures such as tardigrades can survive in extreme conditions such as the vacuum of space and deep under water, how can astronauts and other space flight companies be confident in their means of decontamination after missions and returning to earth?

Question

My initial post was related to more of bacteria or organisms on space suits or moon walks and then flown back to earth in the comfort of a shuttle.

In: Biology

Answer 1

They can *survive* there but they cannot thrive. They don’t have any food, they cannot replicate, grow, or do anything else that’s necessary for long-term living. They just survive in a hibernation-like state.

So far nothing returned to Earth from a place that might have life. If a tardigrade from Earth catches a ride to space and somehow survives re-entry then it had a really hard time just to go from e.g. Florida to the Atlantic Ocean near Florida, or from somewhere in Kazakhstan to somewhere in Russia, or whatever. No harm done here.

If we return samples from Mars then things will get much more difficult. The samples need to be put into a capsule that then enters Earth’s atmosphere. The outer surface will be sterilized by the intense heat of the re-entry, but inside you still have the protected samples. You want to make *really* sure that the capsule doesn’t break open by accident.