Millionaire wants to send humans to Mars (and back) in 2018

2018 is not going to be the year that humans land on Mars. But, if millionaire space tourist Dennis Tito has his way, it could be the first year that humans visit Mars.
Tito has formed a group called the Inspiration Mars Foundation, which is going to try to swing two people around Mars without stopping and then bring them back to Earth on a mission lasting 501 days.
From the press release:
This "Mission for America" will generate new knowledge, experience and momentum for the next great era of space exploration. It is intended to encourage all Americans to believe again, in doing the hard things that make our nation great, while inspiring youth through Science, Technology, Engineering and Mathematics (STEM) education and motivation.
Well, that sounds great, but let’s talk about the details. If we’re going to try and do something like this, 2018 is the year to make it happen due to an aligment of Earth and Mars that won’t occur again until 2031. There’s no landing on the table: the astronauts will be on a free-return trajectory, making a half-orbit of Mars and using the planet’s gravity to slingshot them back towards Earth. It’s the same basic technique that got Apollo 13 safely back home. A trajectory like this is the safest way to do it, although it means that the Mars close encounter will be relatively brief, likely just a few hours out of a mission that will last hundreds of days.
To get there, the Inspiration Mars Foundation is planning on using a deep space version of the SpaceX Dragon capsule, launched on top of a Falcon Heavy rocket. We don’t have a lot of details on the hardware yet, except that the plan is to use existing technologies to support a crew of two for the duration, which likely means the absolute bare minimum of life support. In a 10-cubic-meter space. For 500 days. No variety, essentially no privacy, and nothing to really do except for a day or two in the middle when the two people in the capsule will be the luckiest humans alive. The rest of the time, it’s going to be hellish.
We should point out that it’s 2013 now, and a January 2018 launch means that SpaceX is going to have to have its Falcon Heavy operational and have a deep-space capable Dragon capsule ready to go in less than five years. The Falcon Heavy is supposed to have its very first launch sometime this year, but its first commercial launch won’t be until sometime after 2015 at the earliest. Meanwhile, the crewed version of the Dragon capsule won’t launch until at least December 2015, and that’s just for a capsule designed to get a crew up to the ISS and back, which is nowhere near the level of complexity required to keep two people alive for 500 days.