(NEW YORK) -- In 2001, the millionaire Dennis Tito became the first paying space tourist -- he bought a flight to the International Space Station from the Russian space agency.
Now he's aiming higher. He and a group of fellow space entrepreneurs announced Wednesday that they will try to mount the first-ever flight to Mars, sending a man and a woman to fly past the red planet and return safely in 501 days.
And they say they hope to pull it off by 2018 -- just five years from now, and decades earlier than NASA or anyone else has even contemplated.
Tito, now 72, says he does not plan to fly himself, but he does plan to bankroll part of the mission himself. A former NASA engineer who went into finance to make his fortune, he says the flight would be possible because it would use privately designed spacecraft already in development -- perhaps a rocket and conical space capsule built by Elon Musk's SpaceX company, with an inflatable module made by Robert Bigelow's firm for extra room.
"It's not a commercial mission, it's a philanthropic mission," said Tito in an interview with ABC News.
It would be a tough, dangerous, lonely trip, which is why Tito's group, Inspiration Mars, suggests the crew be a married couple. They would not even land on Mars -- too complicated to organize for now -- just speed by, perhaps getting a look at it from an altitude of 100 miles.
But Inspiration Mars says the excitement of that first foray to another planet would change the world.
"It's a great step for humanity," said Tito. "I think it would be really exciting, not only to our generation, but younger generations as well."
Is it possible, or crazy? Doctors have worried about radiation in deep space; psychologists have fretted about the stress on astronauts alone for more than a year in a cramped ship. And Tito concedes the technical challenges are daunting: "We'd better start burning the midnight oil" to make the flight happen in time.
It so happens that in 2018, Earth and Mars would align in such a way that a roundtrip could be made with relatively little fuel. Another chance like this would not happen until 2031. Inspiration Mars says in a paper that the ship would leave on Jan. 5, 2018, pass Mars on Aug. 20, and be home on May 21, 2019.
That is, if everything works. Can it? Would you and your spouse want to be alone in deep space for a year?
"This 'Mission for America' will generate new knowledge, experience and momentum for the next great era of space exploration," wrote the organizers. "It is intended to encourage all Americans to believe again in doing the hard things that make our nation great."
Copyright 2013 ABC News Radio