What Does A Comet Smell Like? Rotten Eggs & Horses

Science holds the answer to all of our most pressing questions — what are the origins of life? What is the universe made of? And of course, what on Earth does a comet smell like? If that last one has been bugging you for years, look no further for your answer — European scientists have determined that comets smell really bad. But they didn't stop there. Rather, researchers from the University of Bern in Switzerland determined exactly what comets smell like because one person's trash is another's perfume, right? So if you happen to like the smell of rotten eggs and horse urine, you may not be that turned off by a comet's odor after all.

These latest fascinating discoveries were achieved with the help of Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA), which was in March of 2004 for the express purpose of examining the "nucleus and environment of the comet 67P/Churyumov-Gerasimenko." A decade after it first left Earth's surface from French Guyana, ROSINA has finally come close enough to the comet to conduct some serious tests, and is just 5 miles away from the comet's surface. Armed with two mass spectrometers and a pressure sensor, the Rosetta orbiter has the capacity to analyze the comet's atmosphere and measure the density of gasses in and around the comet, among other things.

Thanks to these instruments, ROSINA has been able to catalogue all of the particles and gasses surrounding the comet, and has compiled an impressive laundry list of stinky factors. Kathrin Altwegg, the lead scientist on ROSINA, said in a statement to the scientific community, "The perfume of 67P/C-G is quite strong, with the odor of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odor of formaldehyde." But she doesn't stop there. These delightful smells are "mixed with the faint, bitter, almond-like aroma of hydrogen cyanide." In conclusion, she says,

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.

Rotten eggs, horse urine, formaldehyde, bitter almonds, alcohol, and vinegar certainly doesn't sound like the recipe to the next classic Chanel scent, but regardless of how it smells, an awareness of the compounds that make up the comet are key to determining just how our solar system came into existence. As Altwegg told New Scientist, "This all makes a scientifically enormously interesting mixture in order to study the origin of our solar system material."

This is the first time scientists have been able to come into such close contact with a comet in space, and as such, it is also the first time researchers have ever been able to determine just how awful these objects really are. Initially, Altwegg's team was not expecting such a pungent mixture because P67 remains quite far — 250 million miles, to be exact — from the sun. Without the heat from the large star to warm the comet's surface, scientists assumed that only the most volatile molecules, meaning those that can easily escape from a liquid or gas, would be detectable. But to everyone's surprise, and a few people's delight, P67 was not at all shy about sharing its smells. Altwegg said that such a "rich chemistry at this distance from the sun" was extremely surprising.

Scientists hope to uncover even more secrets about the comet, and by extension, the universe itself when the Rosetta Orbiter deploys its robotic lander, Philae, on November 12. ROSINA has already achieved a number of remarkable firsts, including the impressive feat of becoming the first unmanned spacecraft to go into orbit around a comet. If Philae lands successfully, it will be the first time humans will have such direct access to the surface of a comet's nucleus. Of course, this mission comes with considerable dangers to ROSINA — landing on the comet, whose rocky, icy, uneven surface contains hazardous gasses and other unknowns, will be no easy feat. In 2005, a different spacecraft attempted a comet landing, but the lander simply floated off into space instead of towards the comet.

But if the mission is successful, scientists anticipate exposure to critical information about the origins of water and, more impressively, perhaps the origins of life itself. Landing will not be the final goal of the ROSINA, as the orbiter intends to stay with the comet as it makes its way towards the sun. Matt Taylor, another scientist involved with the project, told Gizmag,

After landing, Rosetta will continue to accompany the comet until its closest approach to the Sun in August 2015 and beyond, watching its behavior from close quarters to give us a unique insight and real time experience of how a comet works as it hurtles around the Sun.

If the mission really does result in new information about the beginnings of our solar system, it seems that a bad smell would be a small price to pay.

Images: Getty Images (2); USATODAY, AllPlanets/Twitter