Elon Musk has called for nuclear weapons to be fired at Mars

Billionaire entrepreneur Elon Musk has called for nuclear weapons to be fired at Mars as a first step to making it habitable for humans.

"Nuke Mars," the Tesla and Space X founder tweeted at the weekend. "It's a step in the right direction".

He even changed his Twitter profile to display the slogan: "Nuke Mars".

The 48-year-old's tweets revisit an idea he first floated in 2015 during an appearance on The Late Show with Stephen Colbert.

"First, you're going to have to live in transparent domes, but eventually, you can transform Mars into an Earth-like planet. You can warm it up," he told Colbert.

"There's a fast way and a slow way. The fast way is drop thermonuclear weapons over the poles."

The original exchange prompted Colbert to label Musk a supervillain.

A recent study in Nature Astronomy discredits Musk's belief about transforming Mars' atmosphere, concluding "terraforming Mars is not possible using present-day technology".

NASA also previously shut down Musk's 2015 suggestion.

"We are also committed to promoting exploration of the solar system in a way that protects explored environments as they exist in their natural state," the space agency said in a statement.

SpaceX hopes to one day transport humans to Mars, with Musk holding the belief that colonising the red planet is imperative for the survival of mankind.