by Thomas Deskins
The gas surrounding comets is mainly affected by two factors. One is the gas' interaction with the solar wind, which is the plasma emitted by the Sun. The other factor is the series of reactions that may occur in the gas. Comets, like planets, emit X-rays through charge exchange reactions between the solar wind and the neutral molecules in its atmosphere. I study the underlying charge-exchange reactions both in the lab and remotely using telescopes like XMM-Newton, NICER on the ISS (pictured below), and Chandra to study the plasma environments of comets
Quite recently, Rosetta observations of comet 67P/Churyumov-Gerasimenko revealed that under certain conditions, electron-impact reactions can be the most important reactions in the comet's atmosphere, also known as the coma. Our research team is developing an experimental set-up to investigate electron-impact dissociation processes, and we collaborate with researchers at the Comenius University in Bratislava (Slovakia) to characterize the light emitted when these electron-impact reactions occur. A major goal of our project is to determine how to use the emission from electron collisions to study gases in comets and the atmospheres of other small bodies, such as Europa.
Acknowledgement: This work is supported by NASA and was done in the lab of Prof. Dennis Bodewits in the department of Physics, Auburn University.