Nadir and Occultation for Mars Discovery

Nadir and Occultation for MArs Discovery (NOMAD) is a 3-channel spectrometer on board the ExoMars Trace Gas Orbiter (TGO) launched to Mars orbit on 14 March 2016.

Nadir and Occultation for MArs Discovery (NOMAD)
OperatorEuropean Space Agency
ManufacturerBelgian Institute for Space Aeronomy
Instrument typespectrometer
Functionatmospheric composition
Mission durationPlanned: 7 years[1][2]
Elapsed: 4 years, 10 months, 13 days
Began operations9 April 2018 [3]
Properties
Mass28.86 kg[4]
Spectral bandUV to visible
Host spacecraft
SpacecraftExoMars Trace Gas Orbiter
OperatorESA
Launch date14 March 2016, 09:31 (2016-03-14UTC09:31) UTC
RocketProton-M/Briz-M
Launch siteBaikonur 200/39
COSPAR ID2016-017A

NOMAD is designed to perform high-sensitivity orbital identification of atmospheric components, concentration and temperature, their sources, loss, and cycles. It measures the sunlight reflected from the surface and atmosphere of Mars, and it analyses its wavelength spectrum to identify the components of the Martian atmosphere that may suggest a biological source. The Principal Investigator is Ann Carine Vandaele, from the Belgian Institute for Space Aeronomy, Belgium.

Overview

NOMAD is one of four science instruments on board the European ExoMars TGO orbiter. This spectrometer consists of three separate channels: solar occultation (SO), limb nadir and occultation (LNO), and ultraviolet and visible spectrometer (UVIS). The first two channels work in the infrared (2.2 to 4.3 μm); the third channel (UVIS) works in the UV-visible range (0.2 to 0.65 μm), which is able to measure ozone, sulphuric acid, and perform aerosol studies.[5][6] Measurements are carried out during solar occultation, i.e. the instrument points toward the sunset as the orbiter moves toward or away the dark side of Mars. It also measures in nadir mode, i.e. looking directly at the sunlight reflected from the surface and atmosphere of Mars.[6][7]

Since 9 April 2018,[3] NOMAD is measuring the existing atmospheric concentrations of gases, their temperature and total densities.[8] Atmospheric methane concentrations below 1 ppb can be detected.[8][9][10] These measurements will also facilitate investigations in the production and loss processes for the cycles of water, carbon, and dust.[8]

NOMAD development and fabrication was carried out by OIP Sensor Systems at Belgium, in collaboration with partners in Spain, the United Kingdom, Italy, US, and Canada.[5][6] Its development was based on the SPICAV spectrometer flown on Venus Express.[10]

Objectives

NOMAD will map the composition and distribution of Mars' atmospheric trace gases and isotopes in unprecedented detail. The specific objectives are: [11]

  • search for signs of past or present life on Mars.
  • investigate how the water and geochemical environment varies
  • investigate Martian atmospheric trace gases and their sources.
  • study the surface environment and identify hazards to future crewed missions to Mars.
  • investigate the planet subsurface and deep interior to better understand the evolution and habitability of Mars.

To achieve these objectives, NOMAD covers a spectral region from UV, visible, and infrared that reveals the signatures of the following molecules and isotopologues: CO2 (including 13CO2, 17OCO, 18OCO, C18O2), CO (including 13CO, C18O), H2O (including HDO), NO2, N2O, O3, CH4 (including 13CH4, CH3D), C2H2, C2H4, C2H6, H2CO, HCN, OCS, SO2, HCl, HO2, and H2S.[8]

In particular, the detection of the different methane (CH4) isotopologues (13CH4, CH3D) will be key to help determine whether they are of geological (serpentinisation, clathrates) or a biological source.[8] In addition, NOMAD can detect formaldehyde (H
2CO) which is a photochemical product of methane, as well as nitrous oxide (N
2O) and hydrogen sulfide (H
2S) which are potential atmospheric biosignatures.[8] SO2, a gas related to volcanism may reveal present or recent volcanic activity on Mars.[8]

See also

References
  1. "ExoMars Trace Gas Orbiter and Schiaparelli Mission (2016)". European Space Agency. 16 October 2016. Retrieved 24 October 2016.
  2. Allen, Mark A.; Witasse, Olivier (2011). 2016 ESA/NASA ExoMARS/Trace Gas Orbiter. Mars Exploration Program Assessment Group. 15–16 June 2011. Lisbon, Portugal. hdl:2014/42148.
  3. Mitschdoerfer, Pia; et al. (9 April 2018). "ExoMars poised to start science mission". European Space Agency. Retrieved 18 June 2018.
  4. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 1—design, manufacturing and testing of the infrared channels. Eddy Neefs, Ann Carine Vandaele, Rachel Drummond, etal. Applied Optics Volume 54, Issue 28, Page 8494. doi:10.1364/AO.54.008494
  5. ExoMars NOMAD instrument. Belgian Institute for Space Aeronomy. Accessed: 13 August 2018.
  6. ExoMars Trace Gas Orbiter Instruments - NOMAD. European Space Agency. 4 November 2016. Accessed: 13 August 2018.
  7. Thomas, I. R.; Vandaele, A. C.; Neefs, E.; et al. (2017). "The NOMAD Spectrometer Suite on the ExoMars 2016 Orbiter: Current Status" (PDF). The Sixth International Workshop on the Mars Atmosphere: Modelling and Observation. 17-20 January 2017. Granada, Spain.: 4401. Bibcode:2017mamo.conf.4401T.
  8. The NOMAD Spectrometer Suite for Nadir and Solar Occultation on the ExoMars Trace Gas Orbiter. (PDF) M. R. Patel, A.C. Vandaele, F. Daerden, R. Drummond, E. Neefs, J.-J. López-Moreno, J. Rodriguez Gomez, G. Bellucci, and the NOMAD team. 2014
  9. Expected performances of the NOMAD/ExoMars instrument. S. Robert, A.C. Vandaele, I. Thomas, Y. Willame, F. Daerden, S. Delanoye, C. Depiesse, R. Drummond, E. Neefs, L. Neary, B. Ristic, J. Mason, J.-J. Lopez-Moreno, J. Rodriguez-Gomez, M. R.Patel, G.Bellucci, The NOMAD Team. Planetary and Space Science. no. 124 (2016) pp: 94–104. doi:10.1016/j.pss.2016.03.003
  10. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2—design, manufacturing, and testing of the ultraviolet and visible channel. (PDF). Manish R Patel, Phillipe Antoine, etal. Applied Optics Vol. 56, No. 10. April 1 2017. doi:10.1364/AO.56.002771
  11. Nadir and Occultation for Mars Discovery (NOMAD). NASA Space Science Data Coordinated Archive. Accessed: 18 August 2018.

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