Chemicals Causing Comet 67P/C-G To Reek Of Urine, Rotten Eggs, Formaldehyde

Chuck Bednar for redOrbit.com – Your Universe Online
If recent chemical signatures detected from 67P/Churyumov–Gerasimenko by the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) are any indication, then it’s a good thing that the forthcoming attempt to land a probe on the surface of the comet is an unmanned mission, because the astronauts might not be able to handle the odor.
The orbiter’s instrument has been using its two mass spectrometers to detect the mixture of molecules contained in the comet’s coma, according to an October 23 blog post by ROSINA science team member Kathrin Altwegg from the University of Bern in Switzerland.
As of September 11, ROSINA had detected water (H2O), carbon monoxide (CO), carbon dioxide (CO2), ammonia (NH3), methane (CH4) and methanol (CH3OH), but a more recent scan had also detected formaldehyde (CH2O), hydrogen sulfide (H2S), hydrogen cyanide (HCN), sulfur dioxide (SO2) and carbon disulphide (CS2).
That combination of chemicals would not make for a very pleasant fragrance.
“The odor of rotten eggs (hydrogen sulfide), horse stable (ammonia), and the pungent, suffocating odor of formaldehyde… is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide,” Altwegg said. “Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulfur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the ‘perfume’ of our comet.”
The ESA team said the detection of this many different types of molecules at this stage of the project has been somewhat of a surprise, according to the AFP news agency. Rosina team scientists believed that only carbon dioxide and carbon monoxide, the most volatile of the molecules found in the comet, would be released through sublimation as its icy surface slowly began to grow warmer.
[ Watch the Video: The Rosetta Mission Asks: What Can We Learn From Comets? ]
“While this is unlikely to be a particularly attractive perfume, remember that the density of these molecules is very low, and that the main part of the coma is made up of water and carbon dioxide, mixed with carbon monoxide,” the ESA said. “The key point, however, is that a detailed analysis of this mixture and how it varies as 67P/C-G grows more active will allow scientists to determine the comet’s composition.”
“Further work will show how 67P/C-G compares with other comets, for example by revealing differences between comets originating from the Kuiper Belt (like 67P/C-G) and comets that hail from the distant Oort cloud (like Comet Siding Spring, which recently flew past Mars),” the agency added. “The goal is to gain insights into the fundamental chemical make-up of the solar nebula from which our Solar System and, ultimately, life itself emerged.”
Earlier this month, the ESA announced that it had completed a comprehensive readiness review and had officially green-lighted the Rosetta mission’s November 12 landing attempt, during which the orbiter’s Philae lander will attempt to touchdown on a landing site located on the smaller of 67P/C-G’s two lobes known as Site J.
The final readiness review took place on October 14, more than two months since Rosetta moved within 100 kilometers on the icy comet. At the time, the spacecraft was just 10 kilometers away from the center of 67P/C-G’s four kilometer body, giving ESA scientists a closer look at both the primary and backup landing sites and allowing them to complete a full hazard assessment less than one month before Philae’s historic attempted landing.
“Now that we know where we are definitely aiming for, we are an important step closer to carrying out this exciting – but high-risk – operation,” Fred Jansen, ESA’s Rosetta mission manager, said in a statement last week. “However, there are still a number of key milestones to complete before we can give the final Go for landing.”
—–
Follow redOrbit on Twitter, Facebook and Pinterest.
—–