Apollo 16’s Charlie Duke and Apollo 17’s Gene Cernan described the smell as “spent gunpowder”. Duke said it was really strong. Talking to Mission Control, Cernan pointed out that it “smells like someone just fired a carbine in here”, referring to the Lunar Module.
It’s true. It smells a bit like that. A bit metallic. Once you smell it, you can taste the metal in the middle part of your tongue. Which is weird, because even while regolith dust looks like gunpowder, its chemical composition is nothing like gunpowder. According to NASA:
Almost half is silicon dioxide glass created by meteoroids hitting the moon. These impacts, which have been going on for billions of years, fuse topsoil into glass and shatter the same into tiny pieces. Moondust is also rich in iron, calcium and magnesium bound up in minerals such as olivine and pyroxene.
But how can the Moon smell if there’s no air there? Astronauts got to smell it inside their capsule. All their suits and clothes were full of the dust that covers the entire Moon. The smell was quite strong, according to them. Jack Schmitt, who flew in Apollo 17 with Cernan, had a reaction to it: “When I took my helmet off after the first EVA [Extra-Vehicular Activity], I had a significant reaction to the dust. My turbinates [cartilage plates in the walls of the nasal chambers] became swollen.”
Mine turbinates were fine, thank you very much, but then again, this was just the smell, not the particles of dust themselves.
In any case, you have to try it yourself. You can visit Beyond Planet Earth: The Future of Space Exploration at the American Museum of Natural History in New York. If you live outside of New York, don’t worry, there’s plenty of time to come: the exhibit spans from November 19 to August 12, 2012.