The Inspiration Mars team have said that the ideal crew for the mission will be, "two professional crew members - one man, one woman - flying as private US citizens."
Jane Poynter added that the crew members they sought should be a 'proven couple,' to help cope with the long trip.
The website for the mission added that, "method of crew selection and specific criteria to be announced at a later date."
More top news
Daniel Cowell has been jailed for five years and four months after ramming a police patrol car with a stolen transit van.
The OPCW have left the site of the suspected chemical weapons attack in Douma and should have results in about a week, ITV News understands.
First Minister Carwyn Jones revealed his plans in his speech at the Welsh Labour conference.