It's been proposed countless times, there are numerous challenges to overcome and the benefits are hard to convince people of.
There's also the issue that it will cost tens or hundreds of billions of dollars to put people on another planet for an extended period of time.
Elon Musk wants to put thousands of people on mars [1] and he's one of the very few individuals with the resources to actually do it successfully. He has had some highly ambitious goals in the past (rocket ship company, electric car company) and has been wildly successful.
NASA supposedly had some funds appropriated to them recently for missions such as researching Mars colonization, they have had plans and discussions of what would be necessary for basic Mars colonization for decades. [2]
There's also the issue that it will cost tens or hundreds of billions of dollars to put people on another planet for an extended period of time.
Elon Musk wants to put thousands of people on mars [1] and he's one of the very few individuals with the resources to actually do it successfully. He has had some highly ambitious goals in the past (rocket ship company, electric car company) and has been wildly successful.
NASA supposedly had some funds appropriated to them recently for missions such as researching Mars colonization, they have had plans and discussions of what would be necessary for basic Mars colonization for decades. [2]
[1] http://www.wired.com/2012/11/elon-musk-mars-colony/
[2] https://www.google.com/search?q=mars+colonization&tbm=isch
https://www.google.com/search?q=plants+on+mars&tbm=isch
http://nextbigfuture.com/2013/12/elon-musk-provides-more-det...