From: neff@iaiowa.physics.uiowa.edu (John S. Neff)
Subject: Re: What planets are habitable
Nntp-Posting-Host: pluto.physics.uiowa.edu
Organization: The University of Iowa
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In article <C659w7.IyD@fs7.ece.cmu.edu> loss@fs7.ECE.CMU.EDU (Doug Loss) writes:
>From: loss@fs7.ECE.CMU.EDU (Doug Loss)
>Subject: Re: What planets are habitable
>Date: Tue, 27 Apr 1993 13:38:28 GMT
>In article <JPG.93Apr27135219@holly.bnr.co.uk> jpg@bnr.co.uk (Jonathan P. Gibbons) writes:
>>I would appreciate any thoughts on what makes a planet habitable for Humans.
>>I am making asumptions that life and a similar atmosphere evolve given a range
>>of physical aspects of the planet.  The question is what physical aspects
>>simply disallow earth like conditions.
>>
>>eg Temperature range of 280K to 315K (where temp is purely dependant on dist
>>     from the sun and the suns temperature..)
>>   Atmospheric presure ? - I know nothing of human tolerance

There are people who have adapted to high altitudes in the Andes and in
Tibet. I suspect that it took them several generations to make the
adaptation because Europeans had difficulty making the adaptation. They
had to send the women to a lower altitude when they were pregnant in order
to insure sucessful childbirth.

>>   Planetary Mass ? - again gravity at surface is important, how much
>>     can human bodies take day after day.  Also how does the mass effect
>>     atmosphere.  I thinking of planets between .3 and 3 times mass of the
>>     earth.  I suppose density should be important as well.
>>

Another factor you should consider is the X-ray opacity of the atmosphere 
in case of stellar flares, the uv opacity is also important because uv 
radiation can kill or damage microbes, plants, and animals. 

>>Climate etc does not concern me, nor does axial tilt etc etc.  Just the above
>>three factors and how they relate to one another.
>>
