Elon Musk is back at it again with his idea of nuking the surface of Mars to terraform it or make it habitable for humans. After tweeting “Nuke Mars!”, Musk is now selling t-shirts on the SpaceX online shop with the same message printed on it.

In an interview at Stephen Colbert’s late-night show in 2015, Colbert and Musk had talked about humans going to Mars. While we all know that Mars is inhabitable for humans, Musk suggested an idea of detonating thermonuclear weapons on the poles to warm the red planet. With all the ice melting, carbon dioxide will be released into its atmosphere, eventually kickstarting a rapid greenhouse effect. He believes this will raise the global temperature on Mars significantly to make conditions livable for humans.

However, a recent NASA study titled “Inventory of CO2 available for terraforming Mars” explored how much CO2 is present in the Martian planet. According to the 2018 paper, the Mars Atmosphere and Volatile Evolution Mission probe, Mars Express spacecraft, Mars Reconnaissance Orbiter and the Mars Odyssey spacecraft, collectively found that there isn’t much of carbon dioxide left on the planet to start off with significant greenhouse warming in the atmosphere. It concluded that terraforming the fourth rock from the Sun is practically impossible with present-day technology.

Musk followed this up on Twitter by saying “there’s a massive amount of CO2 adsorbed into the soil that’d be released upon heating”. Discover Magazine went into a deeper dive with this claim asking the scientists whether this could actually work out. Bruce Jakosky, head of NASA’s Mars MAVEN mission and lead author of the paper, said that although there is adsorbed CO2 in the Martian soil, extracting it isn’t a simple process with present-day technology. Jakosky suggested that there are two possibilities where one could import or manufacture a huge amount of CFC gases to be released in the atmosphere and the second was to build a massive mirror as large as Mars to rapidly heat up the surface, releasing the trapped CO2. And still, the amount of released CO2 won’t be able to achieve a comparable air pressure on Earth at sea level.

Whether the idea of terraforming Mars with nuclear weapons works out or not, Musk’s space company SpaceX has been working on the Starship spacecraft that will eventually transport humans to the moon. The Starship space vehicle will aim to travel to Mars in the future and set up a base on the planet.

SpaceX is working on building two orbital Starship prototypes named Mk1 and Mk2 at facilities in Texas and Florida respectively. An early prototype of the Starship called the Starhopper completed a few tests before and it will be conducting another one soon after it was delayed for “hazard analysis” by the FAA. No date has been announced yet for the next flight test of Starhopper.