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Investigating Titan's Atmospheric Chemistry at Low Temperature in Support of the NASA Cassini Mission
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Author and Affiliation:
Sciamma-O'Brien, Ella(NASA Ames Research Center, Moffett Field, CA, United States);
Salama, Farid(NASA Ames Research Center, Moffett Field, CA, United States)
Abstract: Titan's atmosphere, composed mainly of N2 and CH4, is the siege of a complex chemistry induced by solar UV radiation and electron bombardment from Saturn's magnetosphere. This organic chemistry occurs at temperatures lower than 200 K and leads to the production of heavy molecules and subsequently solid aerosols that form the orange haze surrounding Titan. The Titan Haze Simulation (THS) experiment has been developed on the COSMIC simulation chamber at NASA Ames in order to study the different steps of Titan's atmospheric chemistry at low temperature and to provide laboratory data in support for Cassini data analysis. The chemistry is simulated by plasma in the stream of a supersonic expansion. With this unique design, the gas mixture is adiabatically cooled to Titan-like temperature (approx. 150 K) before inducing the chemistry by plasma discharge. Different gas mixtures containing N2, CH4, and the first products of the N2,-CH4 chemistry (C2H2, C2H4, C6H6...) but also heavier molecules such as PAHs or nitrogen containing PAHs can be injected. Both the gas phase and solid phase products resulting from the plasma-induced chemistry can be monitored and analyzed. Here we present the results of recent gas phase and solid phase studies that highlight the chemical growth evolution when injecting heavier hydrocarbon trace elements in the initial N2-CH4 mixture. Due to the short residence time of the gas in the plasma discharge, only the first steps of the chemistry have time to occur in a N2-CH4 discharge. However by adding acetylene and benzene to the initial N2-CH4 mixture, we can study the intermediate steps of Titan's atmospheric chemistry as well as specific chemical pathways. These results show the uniqueness of the THS experiment to help understand the first and intermediate steps of Titan fs atmospheric chemistry as well as specific chemical pathways leading to Titan fs haze formation.
Publication Date: May 31, 2013
Document ID:
20130013784
(Acquired Jul 03, 2013)
Subject Category: LUNAR AND PLANETARY SCIENCE AND EXPLORATION
Report/Patent Number: ARC-E-DAA-TN8550
Document Type: Conference Paper
Meeting Information: 222nd American Astronomical Society (AAS) Meeting; 2-6 Jun. 2013; Indianapolis, IN; United States
Contract/Grant/Task Num: NNH06CC03B; WBS 399131.02.06.03.27
Financial Sponsor: NASA Ames Research Center; Moffett Field, CA, United States
Organization Source: NASA Ames Research Center; Moffett Field, CA, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: AEROSOLS; ATMOSPHERIC CHEMISTRY; CASSINI MISSION; METHANE; NITROGEN; POLYCYCLIC AROMATIC HYDROCARBONS; TITAN ATMOSPHERE; ULTRAVIOLET RADIATION; VAPOR PHASES
Availability Notes: Abstract Only
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