Comet 67P/Churyumov-Gerasimenko, currently orbiting the sun, was recently analyzed by a team of scientists.
They discovered what a comet smells like by analyzing a mixture of molecules in the comet’s coma – the cloud of particles and gasses around the space rock’s nucleus. The molecules were collected by instruments aboard the Rosetta spacecraft.
The molecules include hydrogen sulphide, hydrogen cyanide, methanol and sulphur dioxide. These can smell like a pungent cocktail of rotten eggs and a whiff of horse stables. In other words, if you could take a whiff of a comet, the smell would give you a serious headache!
https://www.huffpost.com/entry/comet-smells-like-rosetta-probe_n_6042556
