CO2 isotopes on martian atmosphere from planetary Fourier spectrometer (PFS-Mex) data

Introduction: The stable isotope record contained within carbon and oxygen on Mars may provide important constraints regarding the origin of the planet and its relationship to that of other bodies in the Solar System, especially the Earth. Stable oxygen isotopes are particularly useful in the study of Mars because oxygen is abundantly present in both the Martian atmosphere and lithosphere. In particular it is present in CO2, the main constitute (95%) of the atmosphere. Despite their important roles, the precise O and C isotope compositions of Mars’atmosphere remain poorly known and both measurement and interpretation are difficult.. Groundbased and spacecraft studies of CO2 established for C/C and O/O values similar to that of the Earth (the “terrestrial” value) within various uncertainties (Kaplan et al,. 1969; Young, 1971; Maguire, 1977; Schrey,1985;confirmed by Viking measurements reported in Nier and McElroy, 1977). The values reported for the Viking mass spectrometers are for high altitudes (120-180 km), and may not pertain to the bulk atmosphere. Maguire’s results on oxygen are based on the goodness of general fits. Earth-based estimates of O/O show a lighter value (Eiler et al., 2000). Other values found from ground-based observations include those of Bjoraker et al. (1989) on oxygen in water, and Krasnopolsky (1996) . Here we report detection and preliminary analysis of the oxygen and carbon isotopes in CO2 in the Martian atmosphere from the data returned by the Planetary Fourier Spectrometer (PFS) on board the Mars Express satellite.