A multi-millionaire who became the first 'space tourist' in 2001 is expected to announce plans to launch the first manned mission to Mars.

Investment tycoon and former Nasa scientist Dennis Tito made headlines in 2001 after paying $20 million (£13m) to visit the International Space Station, and this week was scheduled to make an announcement about a mission he is funding to send a spacecraft to Mars by 2018.

But documents leaked online suggest that the plans may be even more ambitious than expected, and the craft may be crewed, making it the first manned space mission to venture beyond the Moon.

The plans, which would involve the crew orbiting but not landing on the planet, are expected to be detailed at a press conference by Tito's non-profit Inspiration Mars Foundation in Washington on Wednesday 27 February.

"This 'Mission for America' will generate new knowledge, experience and momentum for the next great era of space exploration," the Foundation said in a statement, "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 education and motivation."

Scientists say that, though highly ambitious, the plans are not impossible to realise, with the Red Planet reaching the nearest point in its orbit to the Earth in 2018, meaning a craft would be able to reach the planet in 225 days, with the return journey taking 275 days.

Nasa currently has plans to send a manned mission to the surface of Mars, but not before the 2030s, with the next time the orbits of the two planets near each other falling in 2031.

The report suggests that the mission would take place in a modified Dragon capsule powered by a Falcon Heavy rocket made by private space flight organisation SpaceX.

The two-person crew would have to endure basic conditions for the mission, with crew comfort "limited to survival needs only".

Tito, who would be 77 in 2018, would be unlikely to take part, as the report states the crew would need significant related experience in, for example, polar bases.

However, Tito believes that the craft should be crewed by a man and a woman, and that "the inspirational aspect and impact on the human population may be enhanced by representation by both genders".