Diagnostics of the atomic and molecular physics of small bodies atmospheres available in the ultraviolet

Ultraviolet wavelengths contain the emission from transitions due to electronic excitation levels of atoms and molecules and as such provide a unique window on the regime where molecules are excited, dissociate, and react which other particles. Examples include fragments that emit at wavelengths that are more easily detectable than their progenitor species (OH for H2O); emission from reactions that are highly diagnostic of electron impact dissociation rates and local temperatures; fragment species that can be used as proxies for species that do not have a dipole moment (atomic oxygen for O2); and the charge exchange interaction of solar wind alpha particles with the neutral gas in small body atmospheres. In my contribution I will summarize how recent results from the Deep Impact and Rosetta missions to comets have opened new windows on UV diagnostics of small body atmospheres, how these diagnostics drive new observations from on and around Earth, and how these observations can be supported by laboratory and computational investigations in atomic and molecular physics.