Interplanetary 'jet lag' and personality clashes could be the biggest obstacles to colonising Mars, British space experts have warned.

Although scientists are still stumped about how to protect astronauts against space radiation, or the physical effects of zero gravity during lengthy voyages, it may be more mundane concerns that hamper lengthy missions.

Last week, experts met in London to consider the social and psychological hurdles to long-term spaceflight, and concluded that one major concern is that crews may simply struggle to ‘get along.’

Previous research has shown that up to half of crews suffer from personality clashes even though astronauts are thoroughly screened for sociability.

“The biggest hurdles to Mars settlement are not technical but psychological," said meeting organiser Dr Federico Caprotti, of the University of Exeter.

“Long-range missions raise psychological questions that current knowledge in space science cannot answer.

“For example, the International Space Station enables a quick return and therefore a sense of psychological closeness to the Earth. Mars does not allow this, and that brings a risk of intense pressure.

“There is also the issue of interplanetary 'jetlag'. The journey could take about 400 days - though experimental plasma engines could speed this up.