A University of Leicester space scientist has described a proposal to send two people on a 501-day round trip to Mars as "dangerous, but important".
Scientist Dr John Bridges was commenting on American multi-millionaire Dennis Tito's plans, unveiled on Wednesday, to send the first manned rocket to Mars in January, 2018.
The independent project, called Inspiration Mars, would cost up to $2 billion (£1.32 billion), does not have funding yet. Mr Tito is searching for a middle-aged couple to be the first tourists to flyby the Red Planet.
He said the likelihood of radiation poisoning was high and the psychological effects of spending 16 months locked in a small capsule with someone meant a married, older couple would be preferential.
Dr Bridges, who is part of the Nasa mission currently exploring Mars using the Curiosity rover, said the ambitious plan was dangerous but important for stimulating independent space exploration.
"We have never returned a spacecraft from a Mars flyby or orbit, so it would be a dangerous to start that with a manned spacecraft," said Dr Bridges. It's certainly extremely challenging and expensive.
"For instance, to protect astronauts in the spacecraft from radiation would probably require extra mass, which would make the launch vehicle more expensive.
"To give an idea of cost, the Mars Science Laboratory (Curiosity) unmanned mission has cost $2.5 billion and took more than 10 years to develop."
The Inspiration Mars mission would have to be ready in just six years.
Dr Bridges said: "I think it is good that entrepreneurs like Dennis Tito are getting involved in space exploration. In the long run, that will stimulate a lot of new activity, even if it doesn't result in a manned mission to Mars by 2018."
The mission has been scheduled for January 5, 2018, to take advantage of an alignment in the planets that occurs once every 15 years.
During that brief window, Mars would be close enough to be able to complete the mission in 501 days and then use the planet's gravitational force to slingshot the spacecraft back to Earth without the need for any course adjustments.
The chosen couple would spend the entire journey in a tiny capsule. They would have about a tonne of dehydrated food and 28kg of toilet paper.
"It's like being locked inside a car without being able to get out," said Josh Barker, from the Space Communication Team at Leicester's National Space Centre. In that space you've got to eat, exercise, wash and go to the toilet, and if you need some time alone there's nowhere to go. It'll be physically and mentally tough.
"The first week after blasting off would be okay, because you'd be able to see Earth and it would be nice and exciting, but after that it would just be black nothingness – a void – until you reached Mars. Then it would be the same thing on the way home.''
