The Role of Temperature-Driven Chemical Reactions in the Evolution of Solar System Ices

Northern Arizona University, Flagstaff AZ

Investigators

Abstract

Many of the icy satellites in the outer Solar System have low surface and subsurface temperatures. Spacecraft measurements at both Jupiter's satellite Europa and Saturn's satellite Enceladus measured various molecular species on their surfaces. Recent work by the Principal Investigator and his colleagues have shown that these molecular species react at low temperatures (~80 K), well within the range of these lower satellite surface temperatures. Using this grant, the investigators will study the role that temperature-driven reactions of ices of different chemical compositions play in the evolution of icy objects within the Solar System. They will use the newly-designed ultra-high vacuum laboratory at Northern Arizona University. Ice samples will be created under conditions similar to those where Solar System ices are found, and then studied as they are heated at various rates. This project supports the mission of the NSF by promoting our understanding of the chemical evolution of icy objects in the outer Solar System. The PI will include graduate and undergraduate students in this research, speak to a local elementary school, as well as give science presentations at the Flagstaff Festival of Science. Ice samples containing oxidants (ozone and hydrogen peroxide) and various sulfur-, carbon-, and nitrogen-containing compounds will be prepared under conditions relevant to Solar System ices and characterized with infrared spectroscopy. Then, the samples will be warmed at various rates, while being monitored with infrared spectroscopy, mass spectrometry and microbalance gravimetry. This combination of techniques allows new products to be identified and the destruction of existing ones to be monitored. Heating the sample at different rates allows for the calculation of the activation energies for the reaction. Finally, the concentration will be varied in these mixtures, which will help to elucidate the reactions pathways that are active in these different chemical systems. The results of this new work will have strong implications on how our Solar System may evolve over time and could change how modelers and theorists view the role that non-radiolytic processes play in the chemical evolution of not only solar system ices but also other objects, such as comets or interstellar ices. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.