Apollo astronauts reported that lunar dust found inside their landers smelt like burnt gunpowder. Since there’s no chemical similarity between moondust and gunpowder, the smell could have been the dust reacting with oxygen and/or water inside the lander, or due to the release of charged particles from the Sun that had become trapped in the dust.

Curiously, though, lunar dust samples brought back to Earth from the Moon are odourless. So whatever caused the smell reported by the Apollo astronauts must have been temporary.

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