Inspiration Mars, a new nonprofit headed by space tourist Dennis Tito, intends to launch two people into a flyby of Mars on 5 January, 2018, on what will set the record for the longest and furthest human spaceflight.
The short timeline, requiring a highly ambitious programme with little testing beforehand, is determined by orbital mechanics. After the 2018 launch date, the next similar opportunity is not until 2031.
"I like to use the expression low-hanging fruit, something that is easy to reach, least expensive to reach," says Tito. "Planets realign every 15 years, and who wants to wait until 2031, because by that time we might have company."
While no spacecraft or launch vehicle has been officially decided - Tito says he is in discussions with a number of possible providers - his calculations used SpaceX's Falcon 9 Heavy launch vehicle and Dragon capsule.
Tito has committed to fund the first two years out-of-pocket, and intends to raise funds for the remainder.
The mission is scheduled to last 501 days, the longest a human has ever been in space. It would also be the furthest from Earth any person has traveled, breaking a record set over 40 years ago by the Apollo crews that circumnavigated the moon.
The crew of two, a married couple according to Tito, will be carefully screened for physical and psychological characteristics. They will be "middle-aged" for both psychological reasons and to cope more favorably with the radiation that all flights outside Earth's protective magnetic belts will encounter.
Partly out of deference to the radiation and partly to reduced crew size, the spacecraft's avionics will be low-tech in comparison to other models, making them both more resistant to radiation and easier to repair.
Such a mission would be considered high-risk with any timeline.