Oxygen isotopes in the martian atmosphere: Implications for the evolution of volatiles

Non-thermal escape of oxygen by recombination of exospheric O₂⁺ combined with diffusive separation of gases at lower altitude provides a mechanism through which the Martian atmosphere may be enriched in ¹⁸O relative to ¹⁶O. Measurement of the abundance of ¹⁸O relative to ¹⁶O together with a determination of the turbopause may be used to develop important constraints on the history of Martian volatiles. Models for the interpretation of these data are developed and discussed in light of present information.