When Rosetta sniffed the gas around Comet 67P, it found a cloud that would have smelled of rotten eggs, ammonia and bitter almonds — and hidden in that cosmic stink were some of the chemical ingredients that may have helped life begin on Earth

When Rosetta sniffed the gas around Comet 67P, it found a cloud that would have smelled of rotten eggs, ammonia and bitter almonds — and hidden in that cosmic stink were some of the chemical ingredients that may have helped life begin on Earth

Between 2014 and 2016, the European Space Agency’s Rosetta spacecraft flew alongside Comet 67P/Churyumov-Gerasimenko and analysed the gas streaming off it. The list of compounds it found reads like a catalogue of unpleasant smells: hydrogen sulphide (rotten eggs), ammonia (a horse stable), formaldehyde, hydrogen cyanide (bitter almonds), and several others. In the same gas were molecules that bear on the question of how life began. Both halves o…