A city on Mars with a million inhabitants could be achievable within 50 years, the space entrepreneur Elon Musk has forecast, as he laid out plans to turn mankind into a multi-planetary species.

The SpaceX founder warned that humans would need to venture away from Earth to avoid a ‘Doomsday event’ and our ‘eventual extinction.’

But he said that a huge Martian city could be established this century, which would not just be an outpost, but a fully functioning society with ‘iron foundries and pizza joints.’

Musk is already planning the first manned flight to Mars in 2023 and has said he wants to die on Mars, although he has stipulated ‘not on impact.’

Under new plans released in the journal New Space, the billionaire said he hoped to build a ‘Mars Colonial Fleet’ of more than one thousand cargo ships which would depart ‘en masse’ could transport 200 passengers at a time, along with materials to build homes, industrial plants and shops.