Apparently, like gunpowder! “It is really a strong smell,” radioed Apollo 16 pilot Charlie Duke. “It has that taste — to me, [of] gunpowder — and the smell of gunpowder, too.” On the next mission, Apollo 17, Gene Cernan remarked, “smells like someone just fired a carbine in here,” reports Science@NASA. Read the rest of the article here. Thanks to Tania.