In describing a comet drifting through space, its smell might be the last thing you'd think about, but Swiss researchers have thought about it, and now they've measured it for one comet -- which stinks.
Scientists say instruments on the European Space Agency's Rosetta comet spacecraft has been analyzing chemicals given off by comet around the 67P/Churyumov-Gerasimenko comet.
As sunlight warms the comet its coma, the gaseous cloud surrounding it nucleus represents a distinctive "perfume," if that the word you'd choose for a noxious concoction of hydrogen sulfide, formaldehyde, ammonia and hydrogen cyanide.
It might be hard to market something smelling like rotten eggs, alcohol, horse pee with some bitter almonds and vinegar thrown in, researchers at the University of Bern reported.
"If you could smell the comet, you'd probably wish that you hadn't," a blog post on the ESA website said.
A mass spectrometer aboard the Rosetta spacecraft has been analyzing the signatures of gasses being boiled off the comet's head.
The comet's "aroma" is more than just a curiosity, say scientists hoping to learn more about the ancient chemical constituents of our own solar system.
"Its perfume may not be Chanel No.5, but comets clearly have their own preferences," researcher Kathrin Altwegg of The University of Bern said.
Most comets likely smell something like Churumov-Gerasimenko, says one scientist not involved in the Swiss research effort.
"In general, you don't want to breathe in comets," says Carey Lisse of Johns Hopkins University. "They are mostly water, but they also have a lot of primitive organics that might smell like the La Brea tar pits."
Whatever the aroma of Comet Churumov-Gerasimenko, it will get stronger as the comet approaches the sun and releases even more gases as it warms further, Altwegg says.
Recent images from Rosetta have shown an increase in activity at the comet.
"At this point, we believe that a large fraction of the illuminated comet's surface is displaying some level of activity," said researcher Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research in Germany.
The comet, with the Rosetta spacecraft in tow, will achieve its closest approach to the sun -- around 114 million miles -- on Aug. 13, 2015.
