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Le 26/06/2018 à 13:22, Jeff Findley a écrit*:
OK, now that THAT objection is cleared you change the subject and admit
that bacteria can survive total vacuum.
Survive in a completely dormant state. Unless something close to earth
normal atmosphere, humidity, and etc. is eventually restored, all of
those examples will not survive in the long term. They will die out.

So, what's the problem with letting a few of them escape on the surface
of Mars where the ratified atmosphere and solar radiation will
eventually kill them?


They have to get a few cm underground and there the radiation is far
less. If they sink to depths of 1 meter they are shielded from radiation.

As Mars exploration advances, we find water under the surface in great
quantities: full frozen lakes are just under a few meters of soil. In
the poles of Mars, NASA retrieved water by just drilling a few cm of soil.

Possibly. Hard to tell how much, if any of it, is actually liquid.

Underground, the bacteria would find a very hospitable environment, with
water, no radiation, and probably a lot of nutrients to go by.

Possibly. Hard to tell until we get there and actually take core
samples.

They can also survive an hypervelocity impact, so even if the spacecraft
crashes and all humans are dead, their bacteria could survive.
Yes, only to eventually die due to lack of atmospheric pressure.


They have to just get underground and they are OK.

Possibly. It really depends on subsurface conditions that scientists
are only speculating about. Again, we need actual core samples that go
down many meters. We've not done that yet, even with uncrewed probes.
My preference would be to do this on crewed missions so that scientists,
on the spot, can examine at least a few of the core samples including
literally putting them under the microscope. This would be orders of
magnitude more efficient than uncrewed probes.

Jeff
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