New insights into impact chemistry through light gas gun integrated in situ mass spectrometry

Impacts are a fundamental process, having shaped the surfaces of all planetary bodies, and modified their contents through impact-driven chemical reactions.

To date, studies of impact-driven chemistry have focused on the materials that remain inside impact craters after the impact event, yet it is within the impact plume - the transient cloud comprising turbulent mixtures of molten and vaporised material ejected from the site of impact - that chemical reactions are most interesting and exotic!

Despite this, impact plumes remain one of the least understood aspects of impact cratering - they have proven difficult to investigate in the laboratory due to their short lifetimes and are impossible to model without vital empirical data to compare against.

Several light gas gun facilities are currently attempting to investigate impact plumes by analysing the bright flash of light emitted by various plume constituents - indeed we have also carried out spectral analyses of the impact plume but find that these methods cannot probe the complete chemistry of the plume since some species may not emit in the spectral region being analysed and some may not be present in high enough abundances to produce detectable emissions.

In order to obtain a complete picture of impact plume chemistry we plan to use mass spectrometry to directly measure the constituents.

Recent technological advances in the field of plasma research have led to the development of small volume, fast sampling mass spectrometers with the temporal and mass resolutions necessary to investigate impact plumes.

By installing such a state-of-the-art time-of-flight mass spectrometer on the two stage light gas gun at the University of Kent, we will be able to perform the first direct, in-situ measurements of impact plumes, facilitating pioneering studies to be made of impact-induced vaporisation, dissociation and ionization, as well as chemical mixing and synthesis.

In particular, we will study plumes resulting from impacts involving a range of water and organic-rich projectiles and targets as the origins of these key ingredients for life have major implications for astrobiology.