Re: How will Mars colonies survive extreme temperature changes?

     Well, as you may know, humans often think of events occuring as if 
they could without an explanation of how it would actually come to pass.  
The colonization of Mars, looking at modern technology, is improbable, if 
not impossible.  Of course, we're always looking ahead (as are the people 
you've heard talking about colonizing Mars).  Here's what we'd need to 
survive on the surface of Mars.  
     First, there's the tempurature, which you asked about.  The surface 
of Mars goes from -120 degrees celsius to 25 degrees celsius.  That's a 
pretty big range.  What we would probably do is set up a fairly large 
structure which would have a structure covered with reflective plates.  
This would take care of the heat problem, because almost no heat energy 
would be absorbed.  As for the cold, the only real answer to that is to 
produce your own heat energy.
     This brings me to the second problem, which is energy.  You need some 
kind of source of energy.  It would be pretty difficult to transport
all the components of a nuclear reactor to Mars, so that idea's out for now. 
Since all other alternatives require large amounts of fuel of some kind, a fuel
source on Mars has to be discovered.  This could be water (which would be the
best), or geothermal energy access.
     Then, you would need food, water, and air.  Without water, this is 
impossible.  Unless some way can be found to shuttle water to Mars easily, 
or to produce water from some other abundant compounds on Mars, water MUST 
be discovered for a colony to exist.
     As you can see, there are a whole load of problems keeping 
us from colonizing Mars.  But keep your hopes up, because as the 
generally uneducated point-maker says, "well, they used to think it was 
impossible to fly...".