A laboratory experiment at NASA's Jet Propulsion Laboratory in Pasadena, Calif., simulating the atmosphere of the ringed planet's largest moon, shows that such chemistry exists lower in the atmosphere than previously thought, suggesting another region on the moon that could brew up prebiotic materials.
"Scientists previously thought that as we got closer to the surface of Titan, the moon's atmospheric chemistry was basically inert and dull," laboratory researcher Murthy Gudipati said. "Our experiment shows that's not true.
"The same kind of light that drives biological chemistry on Earth's surface could also drive chemistry on Titan, even though Titan receives far less light from the sun and is much colder. Titan is not a sleeping giant in the lower atmosphere, but at least half awake in its chemical activity."
Titan has a thick, hazy atmosphere with hydrocarbons, including the organic molecules methane and ethane.
"We've known that Titan's upper atmosphere is hospitable to the formation of complex organic molecules," researcher Mark Allen said. "Now we know that sunlight in the Titan lower atmosphere can kick-start more complex organic chemistry in liquids and solids rather than just in gases."
In previous laboratory experiments, organic molecules like those found on Titan were exposed to liquid water and over time developed into biologically significant molecules, such as amino acids and the nucleotide bases that form RNA.
"These results suggest that the volume of Titan's atmosphere involved in the production of more complex organic chemicals is much larger than previously believed," Edward Goolish, acting director of NASA's Astrobiology Institute, said. "This new information makes Titan an even more interesting environment for astrobiological study."