dtb made some interesting comments:

>Since the main driver will be politics, not science, the possiblity of
>life doesn't have an overhwhelming effect. For humans on Mars by 2050,
>I'd say 40% if the current "warm, wet, and unsubstantiated" paradigm
>holds; 20% if it's dead, Jim; 80% if we find both old aqueous sediments
>and evidence of ongoing hydrothermal activity.

If life is proven to exist on Mars then the likely that people
will be sent there is 0%. The forward and back contamination issues
killed the Mars Sample Return (MSR) project with no hope of recovery.
Sending people to Mars is much more expensive and would include all of
the forward and back contamination issues of MSR. Serious Mars
exploration doesn't begin until the exobiology stuff has run its course.

>Will we STAY, however?
>
>How many people live on top of Everest?
>
>How many people live in Anatarctica?
>
>Better yet, how many on South Georgia Island, which had a thriving
>little whaling community in 1900, but only penguins today. Or in the
>"Empty Quarter" of Saudi Arabia, northern Siberia, or Devon Island?

This is a very interesting point. Look at a map of northeastern
Australia (Queensland) and you'll see towns like Normanton, Mt. Isa,
Burketown, Georgetown, etc. Normanton was a major town and still
occupies a geographically strategic location in terms of commerce and
national defense. Unfortunately almost no one lives there now (I
visited the place years ago). Normanton can actually be quite pleasant
in the right seasons. However it gets very hot and dry during
summer and experiences torrential rain during "The Wet" season. North
eastern Australia once had a signficant population when the copper
mines were still economical. Then the mines ran out and almost everyone
left. California had a similar situation. After the gold ran out,
California depopulated with many of the gold prospectors moving to
Australia in search of easy wealth. California had a significant
Chinese population during the gold rush. However most of the Chinese
went back to China after the gold ran out (same thing happened in
Northern Queensland). Two key points to observe here is economics
and mobility. Now let's confuse the issue. Look at Europe. The
weather is awful in winter. There are too many people there with
serious issues about ethnicity, e.g. Turks in Germany and Algerians
in France. Years of socialism has rotted out much of the social
fabric. Europe is a great place to visit but why would anyone want
to live there? Yet, hundreds of millions of people do and think
they're happy. Millions of Turks living as second class citizens
in Germany could probably achieve an economic miracle in northeastern
Queensland like they did for Germany after World War 2. However
the Australian government would never allow them to immigrate
because those millions of Turks would move straight to Sydney and
queue up at the unemployment office. I guess the main advantage about
Mars colonization is that once the people are there, they have to stay
put. It's too expensive for them to come back to Earth.

Gary