Experimental and theoretical studies on the gas/solid/gas transformation cycle in extraterrestrial environments

• Published in: Journal of Geophysical Research. E. Planets Vol. 106; no. E12; pp. 33325 - 33332
• Main Authors: Cottin, Hervé, Gazeau, Marie‐Claire, Chaquin, Patrick, Raulin, François, Bénilan, Yves
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 25-12-2001; American Geophysical Union
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; Fundamental aspects of astrophysics; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; General, solar nebula, and cosmogony; Molecular and chemical processes and interactions; Solar system; Planetary atmospheres; Comets; Degradation; Methane; Organic matter; Photolysis; Phase transformations; Theoretical study; Chemical evolution; Solar system; Experimental study
• ISSN: 0148-0227; 2156-2202
• DOI: 10.1029/2000JE001319

The ubiquity of molecular material in the universe, from hydrogen to complex organic matter, is the result of intermixed physicochemical processes that have occurred throughout history. In particular, the gas/solid/gas phase transformation cycle plays a key role in chemical evolution of organic matter from the interstellar medium to planetary systems. This paper focuses on two examples that are representative of the diversity of environments where such transformations occur in the Solar System: (1) the photolytic evolution from gaseous to solid material in methane containing planetary atmospheres and (2) the degradation of high molecular weight compounds into gas phase molecules in comets. We are currently developing two programs which couple experimental and theoretical studies. The aim of this research is to provide data necessary to build models in order to better understand (1) the photochemical evolution of Titan's atmosphere, through a laboratory program to determine quantitative spectroscopic data on long carbon chain molecules (polyynes) obtained in the SCOOP program (French acronym for Spectroscopy of Organic Compounds Oriented for Planetology), and (2) the extended sources in comets, through a laboratory program of quantitative studies of photochemical and thermal degradation processes on relevant polymers (e.g., Polyoxymethylene) by the SEMAPhOrE Cometaire program (French acronym for Experimental Simulation and Modeling Applied to Organic Chemistry in Cometary Environment).