Life on Venus.......

Oladele A. OGUNSEITAN oaogunse at UCI.EDU
Tue Feb 20 19:05:45 EST 1996


My statement regarding bacterial survival at 400C and greater 
temperatures actually refers to tolerance and slow growth following heat 
exposure.  The evidence  comes from experiments conducted at the University of
Wales (Cardiff) by Dr. S. Al-Mufti.  E. coli was subjected to flash 
heating 300 through 700C.  

The problem with exobiology is that we expect "monsters" out in space.  
In fact we are in space and the only monsters to be found anywhere are 
already on earth.  The question then is to focus on "unearthly" 
properties of living organisms on earth and trace back their evolutionary 
origins, only with emphasis on environmental parameters that may have 
contributed to the unearthly properties.  I have little difficulty with 
the idea that bacteria can transverse inter-planetary or inter-cometary 
space even with the high level of radiation.  Granted it is difficult but 
not impossible to take samples from comets.  I think the data is worth 
the expense.

	The fact that Karl Stetter & Co find organisms thriving at 120C 
is not evidence that organisms cannot survive at higher temperatures 
elsewhere, in particular with temporary extreme conditions.


- Dele Ogunseitan
UC-Irvine 

On 20 Feb 1996, Dr. David Faguy wrote:

> oaogunse at UCI.EDU ("Oladele A. OGUNSEITAN") wrote:
> >
> >
> >There is evidence for liquid water inside comets.  The only way organisms
> >have the ability to grow at 400C is through adaptation ( real
> >experience).  Sir Fred Hoyle and Chandra Wickramasinghe have a beautiful
> >theory (and some good evidence) for panspermia.
> 

> Most (if not all) microbiologists don't believe there are any bacteria (or archaea) growing at 400 C. Karl Stetter have some that grow around 112 c (I think). The upper temperature limit for life (as we know it) is probably about 120C. Above this the chemical bonds bonds that make biological macromolecules begin to break down (i.e. the peptide bond).  IMHO, the existence of liquid water is necessary but not sufficient for the survival of living organisms (as we know it on earth).

> This of course doesn't mean there aren't pockets of inhabitable environments on Venus (or more likely mars) or that panspermia isn't possible.
> 
> David Faguy
> Exobiology Branch
> NASA Ames Res. Ctr.
> 
> 
> 
> 



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