Oxygen Isotope Mass-Independent Fractionation Processes in the Martian Atmosphere

Oxygen Isotope Mass-Independent Fractionation Processes in the Martian Atmosphere Oxygen Isotope Mass-Independent Fractionation Processes in the Martian Atmosphere The goal of this research is two-fold: 1) to compute the oxygen isotope composition of the modern Mars atmosphere, and 2) to assess the role of atmospheric escape in producing small mass-independent fractionation signatures in both escaping and non-escaping species. The oxygen isotope record of the key volatiles, CO2 and H2O, are of greatest interest, but other less abundant atmospheric species (O3, O2, CO, O, OH) are also important. Photochemical model predictions will be made for the oxygen isotope composition of CO2 and H2O for comparison with published preliminary MSL results. Conversely, the MSL results for CO2 and H2O will allow accurate isotopic photochemical modeling. MSL has not yet reported oxygen isotope values for atmospheric O2, which is a key species for testing various fractionation processes in photochemical models. Measurement of the oxygen isotope composition of upper Earth atmosphere O atoms and ions will be made from LDEF (Long Duration Exposure Facility) metal targets. The LDEF results will be used to measure O fractionation above the terrestrial homopause, which will in turn be used to constrain similar fractionation processes on Mars. The results will be of relevance to the upcoming MAVEN mission. The PI (Lyons) is doing the photochemical modeling using existing computing facilities at ASU. The isotopic measurements on LDEF samples will be done initially with Rick Hervig at ASU using a Cameca 6f ion microprobe. If the ASU 6f is not suited for the work (it is single-collector instrument), the PI will collaborate with colleagues at UCLA or Wisconsin to complete the measurements.