Synchrotron studies of planetary and interstellar ice chemistry

Spacecraft exploration and remote astronomy has advanced our ability to sense the surface compositions of outer-Solar System planets and their moons, comets and interstellar dust grains. A plethora of molecules are seen to reside both in the solid and after release as the surrounding gas-phase; identified by their distinct spectral signatures. Formed by photolysis or fast particle processing of the initial ice components, molecules from basic hydrated species to complex organics have been observed across a variety of icy locations. Of the more abundant molecules observed, water, ammonia, aldehyde and cyanide-type species are of particular interest to astrobiology due to their role in the synthesis of prebiotic species such as amino acids, heterocyclic structures and pyrimidine bases.

To further our understanding of these reactions, we are developing a new instrument at the Australian Synchrotron to mimic the ice chemistry of distant space environments. The setup will compile terahertz and infrared spectra from reconstructed planetary ice systems featuring the molecules listed above. It will allow us to explore intermolecular interactions between the precursors, radiation induced reaction pathways and to probe low-temperature ice morphology. This information will help refine our modelling of chemical processes in cold, distant environments, as well as provide data to assist future telescope surveys and space missions in the search for prebiotic markers.

This research has been funded by the Australian Research Council via a Discovery Early Career Research Award commenced by Dr Ennis in July 2015.