LPL Colloquium: What We’ve Learned About Titan Chemistry from Cassini

Professor Roger Yelle is the scheduled speaker.

Observations by instruments on the Cassini mission have drastically altered our understanding of chemistry in Titan’s organic-rich atmosphere. Synthesis of complex organic molecules occurs at much higher altitudes (lower pressure) and proceeds to much larger molecules than previously thought. Tholins, Titan’s pervasive aerosols, appear to be synthesized primarily in the ionosphere, though a contribution from the stratosphere cannot be ruled out. There is strong evidence that this vigorous organic chemistry is driven primarily by absorption of UV sunlight. The contributions of energetic electrons and ions from Saturn’s magnetosphere is minor and perhaps unimportant, contrary to many pre-Cassini models. Oxygen-bearing molecules are an exception to this and may be due entirely to magnetospheric input. Production and transport of small, stable hydrocarbons is fairly well understood, but much remains to be done to understand the production of the larger molecules and aerosols. The physical processes and chemical pathways involved in the production of these large organic molecules may provide excellent guidance for how a similar chemistry evolved on early Earth.