By Greig Watson
Entertainment reporter, BBC News
The demands of space travel can test astronauts physically and mentally
A mission to restart a failing sun with a Manhattan-sized bomb has the potential to go badly wrong.
But the biggest danger to its success proves to be, not the hostility of deep space or the reliability of the weapon, but the crew themselves.
That is the premise of Sunshine, the forthcoming science-fiction thriller from director Danny Boyle, of Trainspotting and 28 Days Later fame.
"Space is a psychological as well as technical challenge," says 50-year-old Boyle.
"What I told the cast was, apart from the plot, what the film is really about is psychological effect on you of travelling to the sun, the source of all creation.
"Beyond that curtain is the source of all life - and you get to go through that curtain and meet this source, and what that does to your brain and how you cope with that?"
While conjuring a taut, often beautiful thriller, Boyle provides few easy answers to the big questions posed.
"It's hard to talk about this sort of thing without sounding religious, or at least spiritual in a wider sense. For some the experience would have a narrow definition, it would be God.
"What the crew are going into is not a tea party, it's a battle between good and evil."
The space agencies planning three-year manned missions to Mars are acutely aware that lapses by depressed, lonely or disorientated crews could be fatal.
The experiences of the few astronauts to have left Earth's orbit on Nasa's Apollo missions have been dramatic warnings of this.
Tania Burchell, of the National Space Centre in Leicester, said: "Many of them came back changed men.
"It is thought Neil Armstrong could not reconcile everyday life with what had been an epiphany of seeing the world as a single planet and all of us as creatures on it, and yet we still can't get along - and that really got to him.
Mental breakdowns would be a disaster for a space mission
"Another reason is that he didn't like the fact that he was getting all the media attention when there were hundreds of others who made the Apollo program possible - he became a celebrity, while he felt he was just doing his job."
Armstrong's partner on the moon, Buzz Aldrin, came back to a battle with alcoholism while Apollo 14's Edgar Mitchell had a "flash of understanding" which inspired him to research some more obscure scientific beliefs.
The fearsome Alan Shepard, who commanded Apollo 14, admitted to weeping as he walked on the Moon.
Ms Burchell says: "You are in this small tin can crowded with other people. You are under a lot of pressure, separated from loved ones and in an unsettling environment.
"Sleep patterns are disturbed because there is no day and night, just work shifts. People get space sick in the low gravity and many lose their sense of taste as fluid pools in their head, rather like a head cold.
"You can train and train, but there is nothing like really being in space."
Experiments simulating the isolation of a Mars mission have shown that team spirit is vital. Crews are brought together via parties and social functions.
One trick was to have "movie nights" where everyone, including mission control, would sit down to share a film.
Mixed teams are also favoured by Nasa, who see the presence of women as helping to mitigate an environment made up of Alpha males.
Experience on other isolated situations, such as on board nuclear submarines, have shown crews value a leader who is decisive yet understanding.
But actor Cillian Murphy, who plays Capa in Sunshine, explains how the needs of a mission might put strain on these carefully planned scenarios.
"Capa is on the mission because he is the most brilliant physicist of his generation. But you have to consider what that does to your personality, having that intellect.
"It would change your perspective on life. I don't think he is a sentimental person, I don't think he has highly developed social skills."
He added: "This crew have been together for 16 months in a tough environment - and they have to save mankind as an added pressure."
Sunshine opens in the UK on Thursday.