But the biggest problem longterm is that Mars will be a pretty miserable place to live.
Right now you can move to Antartica if you really wanted to. Do you? I don't. And Antartica is a much more pleasant place to be than Mars for many reasons: you can breath the air, it's got water, it's quite a bit warmer, and you get almost twice as much sunlight.
Yes, Antartica is less miserable than Mars. So what? Antartica is, crucially, part of Earth. It is missing the main thing Mars has to make it desirable, which is being another planet. If you don't get the point of ever leaving Earth that's fine, but don't pretend that $random_inhospitable_place_on_Earth is automatically better, for 'being on other planets' purposes, than another planet is.
It is worth splitting the species across multiple planets as some kind of insurance policy. But the long term viability of Earth in the worst of circumstances may still be better than any colony in space or on another planet in our own solar system.
Such a colony would likely be dependent on Earth in many ways for a long long time into the future, and in many ways this may be desirable.
For me the major reason to be positive about space exploration and colonizing space is similar to the reasons why some people will climb mountains: it's there, exploration is in our nature and meeting challenges is something we generally feel positive about. Setting foot on another planet in the solar system alone would be a huge milestone, even if we don't manage to establish a viable outpost.
And for that purpose it doesn't matter much which planet we pick, Mars is for many reasons the best candidate.
Here's to hoping it happens in the next 20 years. It may, it may not, I'm not going to hold my breath but I'm really happy to see some actual progress since 1969 on this front.
I can still hear that roger beep...
Without a plan to make Mars more habitable for humans, Mars will be a lot like ISS or Antartica: a place where a small number of lucky scientists go for a few months before returning home.
If the issues surrounding transit can be addressed, Mars is by far a superior target for colonization.
When scientists talk about "water on Mars", they think they've found a river.
When they hear how far it is, they think it's only twice as far as the moon.
It even has an "atmosphere".
For some reason, people think that it's easier or more useful to build cities on Mars than in the Marianas trench
Last time there was an AMA on Reddit from an antarctic manual worker there were lots and lots of people just asking how they could sign up for it.
http://www.nationalgeographicexpeditions.com/expeditions/ant...