AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Stable Isotope Fractionation in Titan Aerosol Formation
MELISSA TRAINER, Jennifer Stern, Melissa Ugelow, Thomas Gautier, Joshua Sebree, NASA Goddard Space Flight Center
Abstract Number: 327 Working Group: Extraterrestrial Aerosols: from Mars to Titan and Beyond
Abstract Stable isotope ratios of major elements can be used to infer much about local- and global-scale processes on a planet. On Titan, aerosol production is a significant sink of carbon, nitrogen, and hydrogen in the atmosphere, and isotopic fractionation of these elements may be introduced during the advanced organic chemistry that leads to the condensed phase products. Several stable isotope pairs, including 12C/13C and 14N/15N, have been measured in situ or probed spectroscopically by Cassini-borne instruments, space telescopes, or through ground-based observations. However, the effect of a potentially critical pathway for isotopic fractionation – organic aerosol formation and subsequent deposition onto the surface of Titan – has not been considered due to insufficient data regarding fractionation during aerosol formation. To better understand the nature of this process, we are conducting experimental studies of the isotopic fractionation associated with the formation of Titan aerosol analogs via far-UV irradiation of methane (CH4) and nitrogen (N2) mixtures, with and without trace species such as benzene (C6H6). We will report on the effect of temperature and pressure on the direction and magnitude of isotope fractionation for C, N, and H. In addition, a new recirculating experiment allows the gas phase products to be monitored over time as the CH4 reservoir is depleted, providing a comprehensive picture of the gas-phase sinks for carbon and its isotopes. We will present results alongside interpretation of the driving processes for fractionation and implications for photochemical aerosol formation in the atmosphere of Titan, as well as other solar system atmospheres.