Remember Rosetta? It's the European Space Agency mission to drop a probe onto Comet 67P and observe it as it passed around the sun. As the object warmed, it began to emit gasses which, using a pair of mass spectrometers, tell us what the comet is made up of and, more importantly, what it smells like. The ESA already knew that we'd see methane, methanol and ammonia, but were surprised to see hydrogen sulphide, hydrogen cyanide and sulphur dioxide. That means that if you were to stand on the comet and take a deep breath - assuming you hadn't already died - you'd enjoy a heady mix of horse crap, rotten eggs and vinegar. The scientific rationale for the discovery is that we now know a little bit more about how comets are created. But if you ever wanted to recreate the experience of standing atop Comet 67P as it hurtles around the sun, all you have to do is stand outside your local nightclub on a Sunday morning.