Titan, the largest moon of Saturn, has a particular smell, and NASA researchers have recreated the aroma of the giant satellite. Researchers also identified a previously-unknown component in the smog.
The brownish, smoky haze that makes up the thick atmosphere of Titan is largely composed of hydrocarbons, molecules containing carbon and hydrogen. Hundreds of thousands of varieties of this class of molecule are known to exist. The Cassini spacecraft, launched to Saturn in 1997, first detected a mysterious component in the atmosphere of the giant moon.
NASA researchers attempting to recreate the atmosphere of Titan, using just the two most common constituents of the haze, nitrogen and methane, did not produce the same spectral reading as that seen from Cassini. Several other experiments similarly failed to recreate the same composition as that measured for Saturn's largest moon.
Results of the experiments became closer when investigators added benzene, an important component in gasoline, to the mixture. This chemical is in a class chemists call aromatics, and it has been detected in Titan's atmosphere. Other aromatics were also tested, and those containing nitrogen (called nitriles) were found to produce the closest match to measurements of the satellite.
This recipe could simulate the atmosphere on the oversized satellite. Knowing the spectrum of a given mixture of gases, like the ones taken of Titan, is like tasting a pie. What these researchers were doing is akin to taking gases, letting them react, and measuring the result. By comparing one "taste" to another, they can know when their "recipe" is nearly-identical to the original.
The mysterious gas detected by the Cassini orbiter appears to be a type of nitrile called polycyclic aromatic nitrogen heterocycles. These are produced high in the atmosphere of Titan, where they clump together, and precipitate down. Once in lower layers, they become aerosols, and give off the distinctive low-frequency electromagnetic signature detected by the spacecraft.
"Titan's chemical makeup is veritable zoo of complex molecules. With the combination of laboratory experiments and Cassini data, we gain an understanding of just how complex and wondrous this Earth-like moon really is," Scott Edgington, Cassini Deputy Project Scientist at NASA's Jet Propulsion Laboratory, said.
NASA researchers now understand the basic chemistry that is required to recreate the basic chemistry of Titan's atmosphere. Further research will be required to enhance the experiment, and refine environmental conditions in order to better duplicate conditions on the frozen moon.
NASA officials say the air on Titan would smell much like a gas station to a human.
In late 2016, the Cassini probe will take part in a new phase of its mission - soaring above the north pole of the giant planet, and plummeting back down, between Saturn and its rings. NASA is looking for a new name for this part of the flight, and is asking for public submissions.