The O2 vertical profiles in the Martian atmosphere with the ACS-NIR onboard TGO ExoMars.

The molecular oxygen is the minor constituent of the Martian atmosphere with the meanmixing ratio of (1.56 ± 0.06) 10−3. As it is a long-lived incondensable species(with the lifetime ∼60 years) the O2 mixing ratio should have latitudinal variationsinduced by condensation and sublimation of CO2 from the polar caps that result inenrichment and depletion and seasonal variations following the total CO2 amount inthe atmosphere. The O2 column-averaged mixing ratio was provided by severalground-based observations as well as by Herschel orbiting observatory. Now the highprecision measurements of the O2 mean surface mixing ratio were obtained by thequadrupole mass spectrometer as a part of Mars Science Laboratory at the Curiosityrover. The Atmospheric Chemistry Suite (ACS) is a set of three spectrometers (-NIR, -MIR, and-TIRVIM) intended to observe Mars atmosphere onboard the ESA-Roscosmos ExoMars2016 Trace Gas Orbiter (TGO) mission. The near infrared channel (NIR) is a compactspectrometer operating in the range of 0.7–1.7 μm with a resolving power of λ/Δλ ∼25,000. It is designed to operate in nadir and in solar occultation modes. A verticalprofiling of the O2 density based on 0.76 μm band is a unique feature of the ACSNIR science in occultation. No other instrument on a Mars orbiting platform beingsensitive to O2 from 10 to 60 km altitude range. Here we present the first results ofthe O2 density retrievals from the ACS/NIR solar occultations for the first yearof observations and the comparison with the LMD General Circulation model. [ABSTRACT FROM AUTHOR]