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First Results Of The Atmospheric Chemistry Suite (ACS) Experiment On Board The ExoMars Trace Gas Orbiter

Abstract : The Atmospheric Chemistry Suite (ACS), one of four science experiments on board ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission has started science operations in March 2018. ACS consists of three infrared spectrometers targeting the unambiguous detection of trace gases of potential geophysical or biological interest. ACS channels feature very high accuracy (ppt level), very high resolving power (>10,000) and broad spectral coverage (0.7 to 17 μm). The near-infrared (NIR) channel covers the 0.7-1.6 μm spectral range with a resolving power of ≥20,000. This channel is operated in solar occultation and nadir. In nadir NIR is mostly measuring water vapor and dayside oxygen emission. In solar occultation NIR demonstrates profiling of CO2, H2O with high accuracy and in a broad altitude range, and also the molecular oxygen O2, the first ever profiling in the lower atmosphere. NIR observes occultations together with the two other ACS channels MIR and TIRVIM, either together with another spectrometer aboard TGO, NOMAD, and TIRVIM. The mid-infrared (MIR) channel is a high spectral resolution (resolving power of 50,000) instrument dedicated to solar occultation measurements in the 2.2-4.4 μm range. MIR is conceived to accomplish the most sensitive measurements of the trace gases in the Martian atmosphere, allowing also parallel profiling of the abundant components such as CO2, H2O and their isotopologues. The thermal-infrared channel (TIRVIM) is a Fourier-transform spectrometer with cryogenically-cooled detector encompassing the spectral range of 1.7-17 μm. Observing the CO2 15-µm band in nadir TIRVIM returns temperature profiles from the surface up to 50-60 km, together with the dust and water ice optical depth. Also the surface temperature is measured. In solar occultation TIRVIM delivers profiles of CO2, CO, H2O and aerosols, as well allowing to distinguish between mineral and condensate aerosols. ACS has monitored the state of the martian atmosphere before and during the dust event 2018A. The status of the experiment and key findings available by the time of the conference will be reported.
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Submitted on : Monday, February 25, 2019 - 4:27:56 PM
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Oleg Korablev, Franck Montmessin, A. Fedorova, Alexander Trokhimovskiy, N. I. Ignatiev, et al.. First Results Of The Atmospheric Chemistry Suite (ACS) Experiment On Board The ExoMars Trace Gas Orbiter. American Geophysical Union, Fall Meeting 2018, Dec 2018, Wasington, United States. pp.abstract #P31A-02. ⟨insu-02048646⟩



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