Billionaire space tourist Dennis Tito is to fund a manned mission to Mars in 2018.
Tito says he is looking for a middle-aged man and woman for the journey that would last 501 days.
He said the mission will not land on Mars, but would fly within 160km of the planet and then use its gravitational pull to return to Earth.
The BBC reports the couple would receive extensive training and would be able to draw on psychological support from mission control throughout the mission.
Tito said the mission is needed to advance human knowledge and experience.
Tito was the world's first space tourist in 2001 when he paid about $US20 million to spend six days on the International Space Station.
Professor Christopher Riley of Lincoln University believes that sending a couple to Mars might be a good idea.
"The idea of sending older astronauts on longer duration missions, after they have had children, has been around for a while. The reasoning is that such a long duration mission, outside of the protective magnetosphere of the Earth, could leave them infertile," he said.
"Married couples have occasionally flown in space before, on short flights, and it seemed to work well, so why not."
The Mars Inspiration team is aiming for a launch in January 2018 because it coincides with a close alignment of Mars and Earth, when a round trip would take about 501 days.
Otherwise, such a trip might take two or three years.
Tito is financing part of the project, but much more money needs to be raised. The BBC reports that organisers have not stated how much the mission will cost
