Scientists find clues to the mystery of what causes Titan's atmospheric haze

The largest moon of Saturn Titan is more like a planet than a moon in many ways. Outside the Earth, Titan is the only body in our solar system with lakes and surface seas. It also has a thick and nitrogen-rich atmosphere, as well as wind and active weather regimes. All this makes Titan a fascinating subject and a privileged place for future scientific missions.

NASA's Cassini, which has revolved around Saturn for 13 years, has thoroughly studied Titan and gave the researchers a first glimpse of the surface of the moon. But observing Titan's surface is not easy because of the hazy atmosphere around it. Spatial observations show that Titan's atmosphere is rich in complex organic molecules, but the story behind their formation remains largely mysterious.

To better understand the processes and complex chemistry of Titan, the researchers used vacuum ultraviolet light experiments as well as computer simulations and modeling work.

"We are providing here evidence of a low-temperature reaction process that people have not thought of," said study co-leader, Musahid Ahmed, at the Light Source. Advanced (ALS) Berkeley Lab. "."

The researchers detected on the Titan benzene, a simple hydrocarbon with a one-six-carbon molecular structure. It is believed to be a constituent element of larger hydrocarbon molecules with two and three ring structures that, in turn, formed other hydrocarbons and aerosol particles. which now make up the atmosphere of Titan. These multi-ring hydrocarbon molecules are called polycyclic aromatic hydrocarbons (PAHs).

In laboratory experiments, researchers simulated chemical reactions by mixing gases and adding a beam of ultraviolet light under vacuum. The experiments support the hypothesis that three-cycle PAHs do not require high temperatures and provide new clues about the chemical steps that may have produced the Titan web.

"Our study demonstrates that PAHs are more prevalent than expected because they do not require the high temperatures present around carbon stars," said co-directed author, Ralf Kaiser, of the University of Toronto. 39, Hawaii to Manoa. "This mechanism we have explored should be versatile and should lead to the formation of even more complex PAHs."