Earth Years (3 Martian Years) of Mars Observations by NOMAD on ExoMars TGO
Authors: Thomas Ian , Vandaele Ann Carine , Trompet Loïc , Aoki Shohei , Willame Yannick , Piccialli Arianna , Flimon Zachary , Daerden Frank , Neary Lori , Ristic Bojan , Mason Jon , Robert Séverine , Viscardy Sébastien , Erwin Justin , Lopez Valverde Miguel Angel , Patel Manish , Bellucci Giancarlo ,   The NOMAD Team
Published: July 2024

On 21st April 2018, the ExoMars Trace Gas Orbiter began its nominal science phase [1]. Since then, for the last 6 and a half years, the NOMAD instrument has taken more than a 100 million spectra in the ultra-violet, visible and infrared.NOMAD, or &#8220;Nadir and Occultation for MArs Discovery&#8221;, is a suite of three spectrometers: two operate in the infrared and one operates in the 200-650nm range. Of the two infrared spectrometers, &#8220;SO&#8221; is designed primarily for solar occultation observations; and &#8220;LNO&#8221; is primarily designed for nadir observations but can also operate in solar occultation and limb modes [2], and measure Phobos. The ultraviolet-visible spectrometer can do all the above: solar occultation, limb, nadir, and Phobos and Deimos observations [3].The very high resolving power of the infrared SO and LNO spectrometers (~17000 and ~10000 &#160;respectively [4]) mean that they are well suited for measuring atmospheric absorption lines, and are therefore able to measure clouds [5], dust [6], H2O [7], [8], CO [9], [10], CO2 (for temperature and pressure)[11], [12] and HCl [13] in solar occultation mode, plus their isotopes such as HDO [14] and H37CL [15]. SO spectra can also be used to put upper limits on trace gases that are not detected, such as CH4 [16] and HF. In nadir, LNO is primarily measuring H2O [17] and CO [18] in the atmosphere and the albedo/composition of the surface [19], [20]. Work is being done the constrain the potential 2.7&#181;m hydration band in Phobos spectra.The ultraviolet-visible spectrometer, &#8220;UVIS&#8221;, measures O3 and dust/aerosols in both solar occultation [21] and nadir modes [22], in addition to Phobos and Deimos [23]. Of particular note is the ongoing work to observe the limb of Mars during both the day and night, to measure the various airglow emission lines present in the limb spectra [24], [25], [26], [27].Also, calibration efforts are continually ongoing to improve detection limits and retrieval accuracies.In this presentation we will show the latest results from NOMAD, and describe how scientists outside the NOMAD team can also access all the latest data generated by the instrument.&#160;References[1]&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; A. C. 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