The swashbuckling SpaceX founder says that he can get to Mars on a shoestring within 20 years – thanks to the fully reusable rockets he's determined to build

Elon Musk has an unusual new decorative item in his office at SpaceX, the California-based space company he founded in 2002. On his desk are the usual models of the iconic Saturn V rocket and Apollo spacecraft alongside pieces of the SpaceX vehicles Musk envisions as their successors. Photographs of his five children are dotted among the space memorabilia. Hung on a wall there is a large photo of Muhammad Ali. And near it is a very lethal-looking sword. Perhaps it is appropriate given Musk's fearsome reputation as an entrepreneur...

By the age of 30, Musk had set up and sold two companies, including the online payment business PayPal, and he started two more before turning 40: SpaceX, and the electric vehicle business Tesla Motors. The sword was awarded to him in June as part of the Heinlein prize for accomplishments in commercial space activities, set up in honour of the American science fiction writer Robert Heinlein who supported the idea of commercial space travel. "It sure beats your average trophy," says Musk.

The sword is a replica of the one wielded by the swashbuckling hero of Heinlein's novel Glory Road. However, Musk perhaps more closely resembles Valentine Michael Smith, the charismatic protagonist of Heinlein's most famous book, Stranger in a Strange Land. Both are comfortable in the role of outsider, often remaining aloof, almost ethereal; both evince an almost super-human focus and energy. Another link is more obvious. Smith is born on Mars and comes to Earth; Musk would like to be the person who takes humankind to Mars.

That moment may be closer than anyone thinks. Musk declared recently that he could put a human on Mars in 10 to 20 years' time. It is a remarkable claim, yet even more astonishingly Musk tells me that he could do it for $5 billion, and possibly as little as $2 billion - a snip when you consider that the International Space Station (ISS) has cost at least $100 billion to build and operate, or that $2 billion is roughly the cost of launching four space shuttle missions.

To read more, click here.