AST-0908529<br/>Boice<br/><br/>This project will analyze observations of two recent comets, 9P/Tempel 1 (the target of the Deep Impact Mission) and C/2004 Q2 (Comet Machholz), to gain insights into the intrinsic properties of their nuclei and the important physical and chemical processes that occur in their comae. The work uses computational tools developed over the past decades that take into account all relevant physical and chemical processes with sufficient detail not to oversimplify the interpretation of the complex molecular spectra. This includes a global gas dynamics simulation with chemistry, and a time-dependent fluorescence model with collisions and superposition of non-equilibrium states. This is an innovative and unique opportunity to advance our knowledge of parent molecules in comets (including water and simple hydrocarbons), and any compositional variations with depth, gaining clues to the origin of the solar system and possibly the origin of life on Earth. More specific objectives include updating the chemical database of photolytic and gas-phase reactions, and applying the enhanced computational model to the chemistry and composition of the comae of both comet Tempel 1 and comet Machholz.<br/><br/>This study will yield basic chemical data with applications to many fields of science, as has been demonstrated in previous work. The model calculations can be used by observers to search for new species in comets and other astronomical objects. Dr Boice has close ties with the University of Texas San Antonio (UTSA) and San Antonio Community College. This research will inform and enhance his teaching, and provide training for a graduate student, in line with the UTSA goal of becoming a center of excellence in graduate education and research opportunities for Hispanics.