We need to accept the fact that Earth is the only planet we will ever live on.
No matter how far technology advances, no matter how fast and far we fly, it is pretty improbable that we as a species will ever find another planet that suits us like Earth does. Earth is, believe it or not, an environment we are very much a part of, a place that we have spent millions of years adapting to. The cost of that is an extreme disability to survive anywhere other than Earth.
Everything on Earth, from its atmosphere to its climate to its gravity, is a factor that we have evolved around. Our skin blocks the right wavelengths, our lungs tolerate the right gases, our bones handle the right forces. Anything more than a slight deviation to that will be, for lack of better words, the worst thing ever.
On a related note, Mars is hot news right now. The recent rover landing and the aspirations of a certain tech mogul have placed it firmly in the limelight even outside of the scientific community, setting the stage for what just might be the first manned mission to another planet. The problems with human habitation there are, unfortunately, relatively large.
According to NASA, atrophy of the human body occurs rather quickly in space — at a rate of 5 percent a week for muscle and 1 percent a month for bone. Mars is a six-month trip in zero gravity, and once they get there, interplanetary travelers will have to make the difficult recovery process on a planet with toxic dust, no breathable air, high radiation levels and only 38 percent of Earth’s gravity.
And for what? Mars has scientific value in that it is another planet deserving of close study, but harvesting natural resources is nowhere close to feasible from a planet we can barely get to, and leisure travel is even less plausible given the cost and climate (not to mention that large-scale construction could inhibit scientific analysis of the planet). There really just is no good reason to establish permanent habitation on Mars, if that is something our species could even survive.
The best argument for colonizing Mars is to prolong the survivability of humanity in the case Earth becomes inhabitable. If Earth just up and disappears, Mars is the next best thing. Theoretically, this makes sense, but in all honesty, what disaster could possibly befall Earth that would make it less hospitable than Mars? Even if we completely remove Earth’s atmosphere somehow, dooming all life on the planet to extinction, Mars is still more difficult to live on! There is no plausible situation that would make Mars a more viable option for humanity’s survival than simply attempting to fix Earth.
For the life of me, I really cannot conceive of why anyone would actually want to live on Mars. If you want some idyllic utopia, make it here on Earth. If you want the true Mars experience, seal yourself in a radiation bunker and wait to die of heart failure.