The Rosetta mission is about to become the first spacecraft to land on a comet's surface, after a 10 year journey spanning seven billion kilometres.
Along the way, it's found out that its comet smells really, really bad. As Kathrin Altwegg, a researcher at the University of Bern working on the project told NPR: "It stinks."
The European Space Agency (ESA) has posted a list of what makes up 67P/Churyumov-Gerasimenko's "perfume" here, explaining it smells like rotten eggs, horse poo, formaldehyde, vinegar and alcohol. "If you could smell the comet, you would probably wish that you hadn’t :-)", it adds.
As for why scientists didn't realise this before? "That's mostly because we've never been that close to a comet."