Newsgroups: sci.space
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!wupost!howland.reston.ans.net!europa.eng.gtefsd.com!fs7.ece.cmu.edu!fs7.ECE.CMU.EDU!loss
From: loss@fs7.ECE.CMU.EDU (Doug Loss)
Subject: Re: What planets are habitable
Message-ID: <C659w7.IyD@fs7.ece.cmu.edu>
Sender: news@fs7.ece.cmu.edu (USENET News System)
Organization: Electrical and Computer Engineering, Carnegie Mellon
References: <JPG.93Apr27135219@holly.bnr.co.uk>
Distribution: sci
Date: Tue, 27 Apr 1993 13:38:28 GMT
Lines: 35

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
>   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.
>
>Climate etc does not concern me, nor does axial tilt etc etc.  Just the above
>three factors and how they relate to one another.
>
   Dandridge Cole and Isaac Asimov collaborated on a book titled,
"Habitable Planets for Man" (I think) in 1964.  It should be available
in most good libraries, or through inter-library loan.

   It answered the questions you ask (speculatively, of course), along
with many more that need to be considered in habitability studies:
length of day (for day/night temperature variation, and agricultural
concerns), partial pressures of certain unexpected gasses (ever hear of
xenon narcosis?  neither did I), density of particulates in the atm, and
their composition (ever hear of silicosis?  not much fun), etc.

   Climate isn't a global phenomenon and probably needn't concern you,
but axial tilt ought to.  It plays a large part in determining the
severity of seasonal differences, and a lesser but still significant
part in determining the speed of prevailing winds.

Doug Loss
loss@husky.bloomu.edu
