Dr. Vidali and Dr. Pirronello, of Syracuse University, will investigate the formation of molecules in conditions that simulate Titan's environment. The aim is to study physical and chemical processes both in low pressure environments, as in Titan's high atmosphere where aerosol particles form, and in a higher pressure environment where exposed surfaces of condensed material are made by the precipitation of aerosol particles. Dr. Vidali's laboratory has pioneered the use of surface/low temperature physics techniques in the study of the formation of molecular hydrogen on dust grain analogues and in oxidation reaction of H2O-capped CO ice, and the experience of his group can fruitfully be used to investigate similar processes occurring in Titan's environments. One of the most important problems is connected with the removal at the stratospheric level of the very reactive hydrogen atoms that allow unsaturated species like acetylene to form and survive. Drs. Vidali and Pirronello's group will measure the H2 formation efficiency on organic surfaces; on Titan these surfaces are probably maintained in a reactive state by continuous photo-processing. Other important surface reactions to be investigated involve radicals produced by the photodissociation of N2 and CH4, the most abundant species in Titan's atmosphere. Contrary to what happens in the formation of H2 (which ends up with the removal of the product species), the products of reactions with other radicals probably remain on the surface enriching the chemical complexity of the solid phase. The expected results of these experiments will help planetary scientists interpret forthcoming data from the Cassini/Huygens mission.
The potential impact of this research can be significant, since, together with data coming from the Cassini/Huygens mission, the research work detailed here should yield an unprecedented view and understanding of the composition and evolution of the atmosphere of a planetary body besides the Earth. From the educational point of view, it offers both undergraduate and graduate students an opportunity to work in an interdisciplinary field which is at the forefront of research in astrophysics, planetary science and surface science. ***
