Colonising Mars will be as much a challenge of psychology as engineering. Photograph: Denis Scott/Corbis

Since April, thousands of people have applied to take a one-way trip to Mars. Following further stages of selection and training, the plan is for the first four astronauts to lift off in 2022. After a seven-month journey they will settle permanently on the red planet to conduct scientific experiments and do whatever it takes to survive. Meanwhile, the rest of us will be able to watch their lives unfold on reality TV.

The Mars One programme is daring but is it realistic? Nasa is sceptical about a private one-way mission and instead plans to send more rovers followed by a manned return mission sometime in the 2030s. Others have questioned Mars One's business model, technical feasibility and the health risks posed by radiation.

On top of these concerns, Martian colonists will face extreme psychological conditions. Mars One claims to have discussed its plans "with experienced and respected psychologists" but doesn't name them or refer to any supporting evidence. At the same time they have called for applicants who are resilient, adaptable, curious, trusting and creative but without saying why these particular traits are the most important, how they will be measured, or how the standards for selection will be set. Even Professor Raye Kass, who appears to be one of their few advisers on mental health issues, offers little more than anecdotes as evidence for the psychological feasibility of the programme.

Existing research suggests that the colonists will face at least four major psychological challenges. Individually, each of these is serious enough to raise a red flag. In combination, they are a disaster waiting to happen.

Social isolation

The Mars One colonists will be the most isolated humans to have ever lived. Because of their distance from Earth, real time interaction with people back home will be impossible – the shortest delay for sending transmissions will be about 10 minutes. For the rest of their lives they will be able to interact directly with only their fellow colonists, who will increase from three people in the first two years to 23 people after 10 years.

These circumstances will probably cause mental illness in at least some of the colonists. Decades of research shows that prolonged social isolation in astronauts can lead to depression, insomnia, anxiety, fatigue, boredom and emotional instability. Mars One believes that selecting applicants with the right attitude will help prevent such problems. As Kass puts it:

It all starts with attitude. Think of it. When a person finds herself, or himself, on Mars, with no way of being able to come home, and potentially questioning the decision that they have made, what is going to ground them in the choice they have made?

But we know that even the most highly trained astronauts suffer the side effects of isolation – and these are people who know they will be coming home, and who have years (sometimes decades) more experience than the Mars One crew will have. Professor Nick Kanas, a Nasa-funded expert in the psychological effects of space exploration, says that when Earth is out of view for an extended time, "crewmember psychology may result in increased feelings of isolation, homesickness, dysphoria, or even suicidal or psychotic thinking."

The notion that "attitude" will somehow inoculate the colonists against these conditions is at best naive, at worst irresponsible. How will the Mars One programme react when a colonist who was deemed psychologically fit suffers a major breakdown after years of isolation, with no way to get home? Who will be responsible then?

Confinement

A life on Mars will be a life indoors. The atmosphere is unbreathable and the global temperature averages -60C. From the moment they land, the colonists will spend at least 80% of their time within units that offer about 50 square metres per person – that's the size of two average-sized bedrooms. Consider a normal day in your own life and the variety of environments you find yourself moving between, as well as the different sensory experiences you take for granted. Compared with Earth, the colonists will live out their entire lives with a fraction of this exposure.

Not surprisingly, long-term confinement in a small space is associated with many of the same problems triggered by social isolation: depression, anxiety and cognitive impairment, among other symptoms. Animal studies show that captivity can stunt the normal development of young primates, leading to abnormally high fear and reduced exploration behaviours. What does this say about the side effects for children being born and raised in such an environment?

Loss of privacy

While the colonists go about their business, Earth will be watching them 24-7. We already know that surveillance can cause stress, fatigue, depression and anxiety, which will add even more weight to an already extreme mental health burden. The Mars One team has made no public comment on the effects of combining the risk factors of social isolation and confinement with surveillance, but we do know that the programme depends on the money raised by reality TV contracts. So presumably the show must go on.

What happens when the colonists get fed up with the interplanetary Truman Show and turn the cameras off? Will Mars One be forced to abandon them?

Lack of mental health services

Perhaps the most worrying concern is that the colonists won't have real-time access to mental health services such as counselling and psychotherapy. Recent studies have found that simulated psychotherapy via an automated computer programme called Deprexis can yield small-to-moderate benefits in depression, but this approach is only about 50% as effective as normal psychotherapy. And given that the colonists are likely to suffer from a wider range of psychological problems than depression, automated mental health interventions simply won't cut it.

Where does all this leave us? Mars One may be audacious and media-savvy but it is built on a psychological vacuum. In addition to the issues raised here, the planners have given no visible consideration to how they will address the lack of modern medicine, sexual relationships, pregnancy, raising children, ageing and death. And that's not even considering the public trauma on Earth that would follow a televised tragedy on Mars.

Mars One is either ignoring the psychological consequences of colonisation or failing to disclose them. Either way, if their plan goes ahead – and for the sake of the colonists we might hope that it doesn't – then Nasa's manned mission in the 2030s may well be dubbed Mars Rescue.