Ever wonder what a comet might smell like as it journeys through space? Well, wonder no more: the short answer is that it stinks, astronomers say.
That's the verdict provided by the European Space Agency's Rosetta comet spacecraft, which has been sniffing around the Churyumov-Gerasimenko comet for the last couple of months.
Exposure to sunlight is causing an "out-gassing" of a witch's cauldron mix of hydrogen sulfide, formaldehyde, ammonia and hydrogen cyanide with a few other caustic gasses thrown in, researchers report.
The resulting brew would bring to mind rotten eggs, alcohol, horse pee with perhaps some bitter almonds thrown in, European researchers reported.
"If you could smell the comet, you'd probably wish that you hadn't," they said in a somewhat wry blog posted on the ESA website.
An instrument aboard the Rosetta spacecraft, a mass spectrometer, has been analyzing the signatures of gasses being boiled off the comet's head, or coma, as it comes closer and closer to the sun.
As unpleasant as the comet's "aroma" sounds (and likely smells), it has scientists excited for what it may reveal 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 Berne said.
Churyumov-Gerasimenko originates from the Kuiper belt, a region of the solar system extending from the orbit of Neptune outward, and its gaseous makeup can be compared to other comets from the even more distant Oort cloud.
Differences in the content of comets from the two regions could help in understanding the chemical makeup of the solar system as it formed, researchers say.
The Rosetta spacecraft, launched in 2004, arrived in the neighborhood of the comet in August, becoming the first scientific probe ever to go into orbit around a comet.
It is carrying a small robotic lander, dubbed Philae and equipped with its own suite of science instruments, which ESA scientists will guide down to the comet's surface in November.
The comet, with the Rosetta spacecraft following along, will make its closest approach to the sun -- around 114 million miles -- on Aug. 13, 2015.
The comet is named for its discoverers, Klim Ivanovych Churyumov and Svetlana Ivanovna Gerasimenko, who first detected it during a study of telescope photographic plates in 1969.
Its orbital period around the sun is 6.45 years, and it rotates once every 12.4 hours as it journeys through the solar system.
