Stinking 67P Comet

A mix of rotten eggs, alcohol and a horse stable, with a note of bitter almonds – that’s the smell of comet 67P, caught by sensor devices of the Rosetta spacecraft, which is orbiting it, European scientists say.

The comet 67P/Churyumov-Gerasimenko – or Chury for short – is traveling through space some 400 million km (about 250 million miles) from the sun, but this chunk of ice has already started releasing gas molecules. They were detected by the Rosetta orbiter sensor for ion and neutral analysis (ROSINA) – first in August – but this time an unexpectedly much richer picture was revealed.

“The perfume of 67P/C-G is quite strong, with the odor of rotten eggs (hydrogen sulfide), horse stable (ammonia), and the pungent, suffocating odor of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide,” Kathrin Altwegg, head of the ROSINA project at the Center for Space and Habitability (CSH) at the University of Bern, described the smell. “Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulfur dioxide and a hint of the sweet aromatic scent of carbon disulfide, and you arrive at the ‘perfume’ of our comet“.

“What’s surprising is we already have extremely rich chemistry at this distance from the sun,” she added.

To catch up with 67P/Churyumov-Gerasimenko, Rosetta has made a 10-year-long journey, which involved three flybys of Earth and one of Mars. The Rosetta spacecraft has been orbiting the comet since September.

On November 12 at around 09:35 GMT, Rosetta will release its landing probe, Philae – the first manmade object to land on a comet. The historic touchdown is expected to happen seven hours later, and in two hours’ time the first pictures from the surface will be received by scientists at the European Space Agency ESA, as well as two lander control centers in Germany and France.

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