"The Inspiration Mars Foundation, a newly formed nonprofit organization led by American space traveler and entrepreneur Dennis Tito, invites you to attend a press conference detailing its plans to take advantage of a unique window of opportunity to launch an historic journey to Mars and back in 501 days, starting in January 2018. 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."
- New insights on that private (crewed?) Mars mission, NewSpace Journal
Feasibility Analysis for a Manned Mars Free-Return Mission in 2018, Dennis Tito et al, 2013 IEEE Aerospace Conference
"In 1998 Patel et al searched for Earth-Mars free-return trajectories that leave Earth, fly by Mars, and return to Earth without any deterministic maneuvers after Trans-Mars Injection. They found fast trajectory opportunities occurring two times every 15 years with a 1.4-year duration, significantly less than most Mars free return trajectories, which take up to 3.5 years. This paper investigates these fast trajectories. It also determines the launch and life support feasibility of flying such a mission using hardware expected to be available in time for an optimized fast trajectory opportunity in January, 2018. ... We used a mission duration of 500 days (d) in a SpaceX Dragon class of vehicle. Crew size is a primary driver so we compared crew sizes from one to four people, and determined that two crew is optimal given mass and volume constraints."
Keith's update: The mission outlined in this paper uses SpaceX hardware for analysis purposes. As outlined, this conceptual mission would depart Earth on 5 Jan 2018, reach Mars on 20 August 2018, and return to Earth on 21 May 2019. This paper will be presented at the 2013 IEEE Aerospace Conference on 3 March 2013 at 9:50 pm. This paper has been widely circulated for several weeks by the authors and their associates within government, legislative, industry, and advocacy communities, and has been referenced online - in great detail - for more than a week. I cannot post this paper due to IEEE copyright policies. The press event will be webcast live tomorrow at 1:00pm EST. You can sign up at the Inspiration Mars website. There is a Twitter account at @InspirationMars that will become active soon.
Keith's update: Update: this paper is now online at Inspiration Mars Foundation..