Elon Musk is pushing a new idea to make the Mars atmosphere more hospitable to humans. The Tesla CEO believes that it makes more sense to place thousands of satellites (essentially as giant mirrors) to reflect Sun's rays, rather than nuking the poles of the planet. Musk has been positing the “Nuke Mars” idea for the last few years and in fact, he very recently showcased Nuke Mars t-shirts on Twitter. But now, it looks like he may have had a change of heart.

“Might make sense to have thousands of solar reflector satellites ???? to warm Mars vs artificial suns (tbd),” Musk tweeted on Tuesday. By artificial suns, he is referring to his Nuke Mars theory which he explained in a subsequent tweet.

“Nuke Mars refers to a continuous stream of very low fallout nuclear fusion explosions above the atmosphere to create artificial suns. Much like our sun, this would not cause Mars to become radioactive,” Musk wrote.

Musk hopes that by blowing up poles of Mars, enough CO2 will be released to help with heating up the planet and making it more hospitable to humans.

He even defended the “Nuke Mars” theory and called it “not risky.”

“Not risky imo & can be adjusted/improved real-time. Essentially need to figure out most effective way to convert mass to energy, as Mars is slightly too far from this solar system's fusion reactor (the sun),” he explained.

A research paper published in July last year noted Musk's nuclear weapons theory won't work as there is simply not enough CO2 left on Mars in any known reservoirs, including the poles to significantly increase the temperature of the planet. The researchers hope to get a better idea about the presence of hidden CO2 on Mars using the data from ExoMars rover (scheduled for launch in 2020) and the NASA Mars 2020 rover (also launching in 2020).

The tbd (to be discussed) bit in his Tuesday tweet indicates that he hasn't completely given up his “Nuke Mars” theory but he is certainly looking at other options but apart from the one tweet, he hasn't shared any details at this point.

Interestingly, Musk is not the first to propose using some kind of reflectors to heat up Mars surface. In 2006, a University of Arizona undergraduate Rigel Woida won a fellowship to study “study the use of large aperture, lightweight orbital mirrors for 'terraforming' an area of the martian surface so humans could affordably colonize the Red Planet.”

Unlike Musk, Woida was looking to heat a limited area on Mars surface to be able to build a human colony. He planned to “establish a segmented global reflector in orbit around Mars, a 1.5-kilometer diameter array made up of 150 segmented, 150-metre-diameter mylar balloons that would collect sunlight and shine it down over a one-square kilometre area of Mars' surface.”

Hopefully, over the coming days and weeks, Musk will elaborate on his idea of using solar reflector satellites.