‘Vinegar-like perfume': scientists explain why comets smell so terrible

[The title was written by my editor. The comet more likely "smells" like urine and farts.]

The Rosetta probe is sniffing before it scratches the comet it is currently orbiting, and the good thing too—it smells bad.

by John Tyburski

Copyright © Daily Digest News, KPR Media, LLC. All rights reserved.

First published at Daily Digest News on October 28, 2014

Do not expect a comet-inspired fragrance at the makeup counter any time soon. The European Space Agency’s Rosetta probe has entered close orbit with the Comet 67P/Churyumov-Gerasimenko and started sniffing. The Rosetta Orbiter Sensor for Ion and Neutral Analysis, or ROSINA, is using two on-board mass spectrometers to detect the “smell” of the comet.

As the Rosetta probe orbits the comet, ROSINA is detecting the chemical composition of 67P/C-G’s coma, which is the cloud of particulate material surrounding the comet nucleus. As the comet approaches the sun, the coma intensifies, and some of the particulates turn from solid to gas phase while skipping the liquid phase, a process called sublimating.

The comet is currently 250 million miles from the sun, offering enough sublimated coma for the Rosetta team of scientists to get a glimpse of its composition. They expected to detect only carbon dioxide and carbon monoxide, the most volatile substances, but they have detected a much richer variety of compounds.

Last month, the Rosetta team determined that the comet contained water, carbon monoxide, carbon dioxide, ammonia, methane, and methanol. Recent measurements by ROSINA show evidence for the additional, low-density presence of formaldehyde, hydrogen sulfide, hydrogen cyanide, sulfur dioxide, and carbon disulfide. Not only do these compounds smell bad, they are also toxic to humans.

“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,” said ROSINA lead Kathrin Altwegg, “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,” added Altwegg.