Today a group of engineering students from MIT published a very well-researched feasibility study about Mars One, the Dutch plan to put a human colony on Mars by 2024, for a reality TV series.
The study is good, and solid. It basically comes down to "they don't know what they don't know" (the news.com.au headline about the study was "Humans on Mars One mission would start dying in 68 days" which sums it up pretty well). You can read all of the MIT feasibility study here, it's a pretty interesting read.
The elephant in the ballroom here is that Mars One, to date, has raised a grand total of about $600,000 worldwide. With that, they can buy one pretty nice brand-new single engine Cessna, and maybe fuel, a bag of donuts and a thermos of coffee for the flight to wherever a Cessna 172 can get to from Amsterdam.