Elon Musk unveils radical 'megashuttle' that will take man to Mars in 80 days to set up a million person city - but warns first trips will be 'really very dangerous'

SpaceX chief Elon Musk has unveiled his most ambitious project yet - an 'interplanetary transport system' to take man to Mars in 80 days and build a sustainable human colony of a million people there.

'What I want to achieve is make Mars seem possible, to show that we can do it in our lifetimes, and you could go,' he said at the International Astronautical Congress in Mexico.

However, he warned the trip was likely to be dangerous - and said candidates for the first missions 'must be prepared to die'.