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The NOMAD instrument

NOMAD is a 3-channel spectrometer. 2 channels work in the infra-red and build upon the expertise of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB) with its successful SOIR (Solar Occultation in the Infra-Red) instrument which is on-board ESA’s Venus Express mission (VEX). The 3rd channel works in the UV-visible range.

 

Nomad instrument Mars

Nomad instrument Mars

NOMAD’s solar occultation channel (SO) is a copy of SOIR/VEX. The Limb, Nadir and Occultation channel (LNO) is an improved version of SOIR, more adapted for fainter light sources as it will not only measure in solar occultation but also in nadir mode, i.e. looking directly at the sunlight reflected from the surface and atmosphere of Mars. The modified design includes a larger entrance slit to increase the amount of light entering the optics and a new acousto-optical tunable filter to maximise throughput. The UV-Visible channel (UVIS) is based on a design for a previous Mars lander made by the Open University, UK. It will measure in both solar occultation and nadir modes.

Below is a video showing the NOMAD design:

Three models of the instrument were built, as required by ESA:

  • Structural-Thermal Model (STM): This is a representative model of NOMAD, having the same size, mass, centre of gravity of the real instrument, but without any optical components. This was mounted to the spacecraft before the real flight model was completed, so that the satellite could undergo thermal and structural tests with a representative load without having to wait for the real instrument
  • proto-Flight Model (pFM): This is the instrument that will fly to Mars. The model underwent a wide range of tests to ensure that it will survive the journey to Mars and will work as expected once there.
  • Flight Spare Model (FS): This is an identical copy of the pFM, which is built in case there is a problem with the flight model that cannot be easily solved. The window for launching to Mars only opens every 2 years, and so if a problem occurs a replacement is needed immediately. In the case of NOMAD, we discovered that the detector in the LNO channel was not working correctly, so it was replaced by the detector from the flight spare model. Without such a backup, NOMAD would have likely been sent to Mars without a functioning LNO channel!

 

Nomad STM
NOMAD STM

NOMAD pFM
NOMAD pFM

NOMAD FS
NOMAD FS

 

NOMAD development and construction was carried out by the prime contractor, OIP, Oudenaarde, in collaboration with expert partners in Spain, the UK and Italy. The central electronics unit and firmware were designed by Spanish colleagues who worked on Rosetta, Mars Express and Venus Express, and were built by Thales Alenia Space Belgium (also known as ETCA). UVIS was designed and built by Lambda-X, Nivelles; its electronics were designed and built by the Mullard Space Science Laboratory, UK.

The Royal Belgian Institute for Space Aeronomy (BIRA-IASB) designed much of the SO and LNO channels, including the electronics and ground support equipment. The institute also managed all of the tasks carried out across Europe and maintained the documentation necessary for ESA. They also took care of the planetary protection aspects necessary for missions going to Mars, alongside their project management responsibilities. Testing and science performance were also the responsibility of the institute.

 

NOMAD menu

 

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