In 1965, four years before Neil Armstrong even set foot on the Moon, the SNAP-10A became the first and only US nuclear-powered satellite, operating in Earth orbit for 43 days.\u00a0<\/p>\n
Since then, nuclear devices have powered deep-space missions like Voyager<\/a> and even the Mars<\/a> rover, Curiosity.<\/p>\n Some have been based on lower-power systems known as radioisotope thermoelectric generators (RTGs) \u2013 like astronaut Mark Watney\u2019s \u2018space battery<\/a>\u2019 in the 2015 film The Martian, which converted heat from radioactive decay into electricity.<\/p>\n There are also radioactive heaters in two Russian rovers left stranded on the Moon.\u00a0<\/p>\n To generate more power for lunar bases, NASA has turned to small-scale fission systems: splitting the atom.<\/p>\n In 2018, it completed successful tests<\/a> of its toilet roll-sized, uranium-powered reactor \u2018Kilopower\u2019, claiming that four of these devices could run an outpost on the Moon.\u00a0<\/p>\n While \u2018nuclear reactor on the Moon\u2019 might sound risky, these designs prioritise safety: they use passive cooling and low-enrichment uranium, making catastrophic failure extremely unlikely.<\/p>\n Still, its demise is a fascinating hypothetical.<\/p>\n What if it blew up?<\/p>\n We\u2019ve really no idea what a nuclear meltdown on the Moon would look like \u2013 and, with current plans, there\u2019s no indication it would even be big enough to be considered a meltdown.<\/p>\n (One Kilopower reactor would only supply enough power for several Earth houses over about 10 years.)<\/p>\n But we can speculate, of course. It\u2019s not just the size of the reactor that determines what happens if it blows \u2013 it\u2019s the environment.<\/p>\n A reactor accident on the Moon would unfold very differently to one on Earth.<\/p>\n As the Moon has no atmosphere, no weather and one-sixth of Earth\u2019s gravity, we might expect that instead of the explosion, mushroom cloud and aftershock (triggered by reactions with molecules in the Earth\u2019s atmosphere) it would be something somewhat less dramatic.\u00a0<\/p>\n Instead, the reactor might simply overheat, perhaps producing an initial flash, then a glowing pool of molten metal that cools and solidifies in silence.<\/p>\n That\u2019s not to say that such an event wouldn\u2019t be dangerous for anyone manning the station. They would still be exposed to a strong surge in radiation.<\/p>\n That radiation would still be dangerous nearby, but without air or wind to carry radioactive dust, fallout would remain largely local.<\/p>\n A near miss<\/p>\n Thankfully, we don\u2019t have a better answer to the question, though we might have done if certain US scientists had got their way back in the 1950s.<\/p>\n Project A119<\/a> was a secret plan to drop a hydrogen bomb on the Moon as part of the escalating \u2018space race\u2019 between the US and the Soviet Union.<\/p>\n Fortunately, it never really got beyond the planning stage.<\/p>\n This article is an answer to the question (asked by David Martin, Worle) ‘What would a nuclear meltdown on the Moon be like?’<\/p>\n To submit your questions, email us at questions@sciencefocus.com, or message our Facebook<\/a>, X<\/a>, or Instagram<\/a> pages (don’t forget to include your name and location).<\/p>\n Check out our ultimate fun facts<\/a> page for more mind-blowing science<\/p>\n Read more:<\/p>\n![\"SNAP-10A,](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/02\/nuclear-meltdown-moon-SNAP_10A_Space_Nuclear_Power_Plant.jpg\")
SNAP-10A, the first nuclear power system to operate in space, was launched into Earth orbit in 1965 – Image credit: Atomics International\/Contractor to US Atomic Energy Commission<\/p>\n