You’d assume the surface of an airless, lifeless ball of rock 240,000 miles from Earth wouldn’t smell like anything. Apollo astronauts found out otherwise. Once they came back inside the lunar lander after walking on the Moon, they noticed something unexpected - a sharp, metallic smell. Multiple astronauts independently described it the same way: it smelled like spent gunpowder.
Moon dust, called regolith, turns out to be unlike anything on Earth. It’s made of incredibly fine, sharp particles - basically jagged glass shards, formed by billions of years of micrometeorite impacts on the lunar surface. With no wind or weather to round them off, these particles stay needle-sharp.
That sharpness causes problems. Moon dust scratched spacesuit visors, jammed lunar rover wheels, and was nearly impossible to clean off equipment. It also makes the dust easier to chemically react with the air inside a spacecraft. Most scientists now think the gunpowder smell was the dust reacting with oxygen in the cabin - releasing chemicals that triggered the astronauts’ sense of smell in a very familiar way.
