It used to be that he only sought to put a man on Mars. Now, SpaceX Founder Elon Musk has expressed his desire to build a self-sustaining metropolis on the red planet.

Musk shared his vision of Mars as Earth's "backup" at the AeroAstro 100th Anniversary Symposium, held October 22 to 24 at the Massachusetts Institute of Technology.

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"A multi-planet version of humanity's future is going to last a lot longer than if we were a single-planet species," he said at the centennial celebration. Musk adds that, while he agrees present life on Earth should remain top priority, it wouldn't hurt to direct small efforts toward civilizing Mars.

"Some risks are extremely difficult to mitigate, and some we ultimately may not be able to mitigate," he added. "The question is, should we [colonize Mars] now, or wait for some point in future? I think the wise moment is to do it now."

Even though SpaceX has only been around for 12 years, the company has already secured collaborations with the National Aeronautics and Space Administration (NASA).

On Saturday, its Dragon spacecraft will conclude its fifth trip with the Falcon launch vehicle (also SpaceX's) to the International Space Station. The Dragon taxied 20 mice that have now taken residency of the outpost.

Musk, who has never shied from expressing his seemingly out-of-this-world ambitions, is also the man behind electric car manufacturer Tesla Motors and online money service Paypal.

Ironically, it was MIT's Department of Aeronautics and Astronautics that disputed the feasibility of the Mars One project, dubbed "the next giant leap for mankind", with an independent assessment released in September.

The researchers confirmed a "one-way" ticket for the first humans to leave Earth in 2024, pointing out starvation as their most probable cause of death.

TagsElon Musk SpaceX, Elon Musk Tesla, tesla motors, SpaceX Founder, NASA, SpaceX, Mars Metropolis, Mars City, Masschusetts Institute of Technology