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| Titel |
Science objectives and Expected performances of NOMAD, an ExoMars TGO instrument |
| VerfasserIn |
Séverine Robert, Ann Carine Vandaele, Ian Thomas, Frank Daerden, Cédric Depiesse, Rachel Drummond, Lori Neary, Yannick Willame, Josè Juan Lopez-Moreno, Julio Rodriguez-Gomez, Manish R. Patel, Giancarlo Bellucci |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250110150
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| Publikation (Nr.) |
 EGU/EGU2015-10125.pdf |
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| Zusammenfassung |
| NOMAD, the "Nadir and Occultation for MArs Discovery" spectrometer suite will be part
of the payload of the 2016 ExoMars Trace Gas Orbiter Mission. This instrument
suite will measure the atmosphere of Mars in the infrared, visible and ultraviolet
regions covering 0.2 – 0.65 and 2.2 – 4.3 μm. It is composed of three channels: a
solar occultation only channel (SO) operating in the infrared wavelength domain, a
second infrared channel capable of doing nadir, but also solar occultation and limb
observations (LNO), and an ultraviolet/visible channel (UVIS) that can work in
all observation modes. Thanks to its very high spectral resolution and multiple
observational modes, NOMAD will be able to detect a wide range of atmospheric
trace gases, many of which are important markers of geophysical and/or biogenic
activity.
While the instrument is being assembled and tested, scientific preparations have begun.
ASIMUT-ALVL, a line-by-line radiative transfer code developed at IASB-BIRA, is used to
simulate spectra in the infrared range (0.7 — 4.5 μm) as would be measured by the
instrument and under various atmospheric conditions obtained from the IASB-BIRA GCM,
GEM-Mars. Random noise has then been added to the simulated spectra to match the real
instrument characteristics of each channel: SNRs have been derived using a model that
simulates the real instrument (e.g. transmission properties of optical components, expected
in-flight instrument temperatures, detector responsivities, etc.). After NOMAD has been
calibrated and tested, these values will be amended to match the ground-calibration
results.
ASIMUT-ALVL has then been used to perform retrievals on the noisy spectra. In order to
establish detection limits of trace gas and key isotopologues such as CH4, C2H2,
C2H4, C2H6, H2CO, H2S, H2O, HDO, CO, HCl, HCN, N2O, NO2, O3, OCS,
SO2, or NH3 we had to define the best spectral ranges (both in the UV and IR) to
be studied for each molecule and each observation mode. These results will be
presented. |
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