Mission scientist reacts to historic first images from the surface of a comet

If it were possible to breath in space, one would smell a pungent aroma of rotten eggs, ammonia, vinegary sulphur dioxide and toxic hydrogen cyanide coming from comet 67P/Churyumov–Gerasimenko, according to sensors on the Rosetta mission.

Europe’s Rosetta mission ended its 12-year mission Friday with a slow-speed belly-flop on comet 67P/Churyumov-Gerasimenko, concluding an interplanetary odyssey that gave humanity a first close-up introduction to a class of objects which has stimulated imaginations for millennia.

While 2014 was the year the Rosetta spacecraft celebrated making it into orbit around a comet, 2015 was the year it got down to some serious hard work. Its comet, with the tongue-twisting name 67P/Churyumov–Gerasimenko, made its closest approach (186 million kilometres) to the Sun, a period known as perihelion when the comet would be expected to be at its most active. Rosetta was there to witness this.