NASA is seriously thinking about this: Now Nasa looks to change Mars into a garden of Earthly delights
Within a couple of decades, Mars could be habitable to life. The current idea is to station large mirrors that concentrate sunlight on the polar caps, releasing carbon dioxide, thickening and warming the Martian atmosphere. (Carbon dioxide is a green house gas). The concern that some scientists have is that in terraforming Mars, we would not only be harming our planet but also another planet. Plus they argue that with the recent rover evidence of water and methane (a byproduct of biological life), terraforming Mars would be unethical.
I think life on Mars, even possibly living bacteria (as possibly shown by the methane release), will be discovered this year or the next. This life should thoroughly be classified and categorized to see if and how it fits into Earth’s taxonomy. Will life on Mars have the same genetic makeup, consume the same nutrients, or use the same amino acids? These types of questions should be answered and explored. But then, I would love to see Mars terraformed. Can you imagine in the not-so-distant future, traveling to Mars for vacation?? Humans are rapidly consuming resources and land on Earth. Mars would be a great place to expand humanity.
Currently we (humanity) has all its eggs in one basket. Expanding to another planet would be the smartest way to increase our species chances of survival in the next millenia. If not a habitable destination for a long time, at least it would provide another off earth starting point for space travel. New telescopes orbiting Mars (or on the moon) would provide clearer images of the universe at Creation.
Plus, it would be just plain cool. Imagine having to indicate on the destination of mail, not only the country but the planet as well? I heard somewhere that the gains in the previous century (1900-2000), while great, will be incomparable to the gains made in the next century (2000-2100). My great-grandparents went from horse and buggy to the advent of space travel. I believe that the next century will build off of space travel. The great triumphs of the next century will be huge advances in space travel, medical breakthroughs in cancer and viral diseases (though new treatments will need to be developed to combat increases bacterial resistance to antibiotics), and quantum computing on a level that defies Moore’s Law.