Scientists at the European Space Agency have discovered the smell of a comet: rotten eggs, urine and formaldehyde.

In their blog the scientists commented, "If you could smell the comet, you would probably wish that you hadn't," and added that these chemicals were also mixed with the aromas of alcohol and vinegar, to create a pungent cocktail.

The molecules involved include hydrogen sulphide, ammonia, hydrogen cyanide, methanol and sulphur dioxide, and scientists have been 'sniffing the fumes' of comet 67P/Churyumov-Gerasimenko since early August, using space probe ROSINA.

The aim of the investigation is to detect the mixture of molecules in the comet's coma with a view to eventually detailing the chemical composition of the comet itself as it moves closer to the Sun.

Eventually scientists hope to compare comets which have come from different areas of the Solar System, and they describe their goal as "to gain insights into the fundamental chemical make-up of the solar nebula from which our Solar System and, ultimately, life itself emerged."

The Rosetta mission was launched in 2004 and in November this year hopes to deploy a lander on the comet for further investigation, before the mission reaches its end on 31 December 2015.