The tardigrade, extreme resistance and cryptobiosis

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Janic
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by Janic » 07/03/13, 15:31

interesting, but according to the observer their resistance to heat does not exceed 120 ° which excludes an entry into the atmosphere by meteorite.
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by Christophe » 07/03/13, 15:32

120 ° C even when in cryptobiosis?
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by sen-no-sen » 07/03/13, 16:36

Janic wrote:interesting, but according to the observer their resistance to heat does not exceed 120 ° which excludes an entry into the atmosphere by meteorite.


False.
Only the surface of the asteroid heats, more in the center of it it is quite possible to have temperatures allowing the survival of microorganism.
Only the upper layers rise in temperature.
As for the tremendous pressure on impact, NASA has performed tests demonstrating the survival of bacteria despite extremely violent shocks, so it is quite possible.
Last edited by sen-no-sen the 07 / 03 / 13, 16: 42, 1 edited once.
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by Janic » 07/03/13, 16:41

Only the surface of the asteroid heats, in the center of it it is quite possible to have temperatures allowing the survival of microorganism.
it's just a guess!
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by sen-no-sen » 07/03/13, 16:48

No it's physics!
Only the part subject to the friction of the air enters temperature.
In the case of a large mass asteroid, it is quite possible that fragments arrive on the ground without having been sterilized by high temperatures.
A comet would be a good carrier, because mostly made of ice.
Warning! I said it was physically possible and not that it was inevitably likely.
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by Janic » 07/03/13, 17:36

so where it is essentially ice and melting is almost immediate when entering the atmosphere, or the beast is deeply embedded in the rock, which does not seem to correspond to what is said ie a surface presence. Or it would take a huge mass!
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by sen-no-sen » 07/03/13, 18:27

Janic wrote:so where it is essentially ice and melting is almost immediate when entering the atmosphere, or the beast is deeply embedded in the rock, which does not seem to correspond to what is said ie a surface presence. Or it would take a huge mass!


Some astroblemes suggest masses of several million tons of rock on earth.

The largest dimension of the Halley Comet core, oblong in shape, is about 15 km; the volume of its nucleus was estimated at 500 km3, for a mass of 10 ^ 14 kg, which corresponds to an average density of 200 kg / m3.

http://fr.wikipedia.org/wiki/Com%C3%A8te

A large amount of ice would not have time to melt during the short re-entry period.

FYI, ESA experiments have shown that lichens can live nearly one and a half years in the terrestrial orbital space environment.
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by Christophe » 07/03/13, 20:15

which corresponds to an average density of 200 kg / m3.


I did not know this fact! It is a very low average mass, 5 times less than water, 10 times less than "earth", 40 times less than steel ...

This means that a comet contains a lot of "void" (filling up with air in the atmosphere) therefore a material which is a priori well thermally insulating therefore quite possible that bacteria can survive there during atmospheric reentry ... especially given the mass (therefore inertia) involved ...

ps: 500 km3 for a perfect sphere this would correspond to a radius of (V = 4⁄3 × π × R ^ 3) 5 km ... but to a cube of 15 km side ...
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by Gaston » 08/03/13, 09:31

Christophe wrote:ps: 500 km3 for a perfect sphere this would correspond to a radius of (V = 4⁄3 × π × R ^ 3) 5 km ... but to a cube of 15 km side ...
Only 8 km for the cube ... : Wink:
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by Christophe » 08/03/13, 09:45

Ben shit, my power 1 / 3 visibly kidding ...

Yes 8 km sorry (15 km it seemed a lot ...)!
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