United Kingdom, May 9 -- Elon Musk's plan for humans to colonise Mars is "life insurance" for planet Earth.

The billionaire businessman hopes to use his SpaceX company to establish a self-sustaining base for humanity on Mars to ensure the long-term survival of the human race before the Earth is eventually destroyed by the Sun - and he's now declared he sees the scheme as necessary even though it's proving to be "very difficult".

During an interview with Fox News' Jesse Watters, Musk explained: "Going to Mars to build a self-sustaining civilisation on Mars, that is a very difficult thing which SpaceX has not yet done. And we've yet to send anything to Mars."

He added: "It's not about going to Mars to visit once, but it is to make life m...