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Scientists reveal the unholy stench of a comet


Best to keep your distance from the comet’s deathly pong

Think about the worst smells you’ve ever smelt. Now, mix them all together with an added dash of month-old milk and you’ll be somewhere close to matching the stench of a comet hurtling through space.

The pungent discovery comes from Rosetta, a European Space Agency probe into the catchily-titled comet 67P/Churyumov-Gerasimenko. The satellite has been sampling the comet’s scent since early August, comparing the aroma to rotten eggs and horse manure.

Kathrin Altwegg, a lead scientist on the project, explains: “The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde.

Rotten eggs, formaldehyde and almonds?!

“This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the ‘perfume’ of our comet.”

Rosetta is the first satellite to ever begin orbiting a comet, which it will do for a year, although by the sounds of things it may have got more than it bargained for. The comet’s deathly pong may seem a minor discovery in the enormity of outer space, but the overall goal of the project is much bigger – hoping to gain insights into the fundamental chemical make-up of the solar nebula from which our Solar System and, ultimately, life itself emerged. Much more than just a smelly lump of rock in space, then.

Follow the Satellite’s progress over on the Rosetta Blog.

Photo: Dabarti CGI /
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