The Physics and Chemistry of Comets / Dr Steven Charnley (Astrochemistry Laboratory, Solar System Exploration Division, Code 691, Science and Exploration Directorate, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA)

Abstract
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I will summarize what is currently known of the chemistry of comets. Sublimation of nuclear ices near perihelion generates the coma - a multi fluid plasma whose understanding requires consideration of a variety of chemical processes. Compositional studies, from ground and space, especially of organic molecules, isotopologues, and ortho-para ratios can provide important clues as to their origins, and to their possible role in providing water and biomolecules to the early Earth.

Mumma, M. J. & Charnley, S.B. (2011), Annu. Rev. Astron. Astrophys., 49, 471.