What is the ExoMars Trace Gas Orbiter (TGO)?

About ExoMars Trace Gas Orbiter (TGO):

• TGO is the first in a series of joint missions between the European Space Agency (ESA) and Roscosmos, the Russian space agency.
• Goal: To gain a better understanding of methane and other atmospheric gases that are present in small concentrations (less than 1% of the atmosphere) in the Martian atmosphere. 
• The orbiter’s sensitivity to hydrogen has also allowed it to search for water buried underneath shallow layers of Martian soil.
• It’s also meant to test technology for future missions.
• It was launched in March 2016 and began operations after entering Mars orbit on Oct. 19, 2016.
• TGO carried the Schiaparelli lander with it to Mars. However, it was crashed during landing.
• The spacecraft itself is a 3.2 meter by 2 meter by 2 meter box, fitted with one antenna to communicate with Earth and another to communicate with spacecraft on the surface of Mars. 
• It is powered by a pair of solar arrays that protrude from its sides like wings, along with two small batteries to keep it running during eclipses, when it doesn’t receive any sunlight.
• It carries several instruments including,
  • NOMAD (Nadir and Occultation for MArs Discovery);
  • ACS (Atmospheric Chemistry Suite);
  • CaSSIS (Colour and Stereo Surface Imaging System);
  • FREND (Fine Resolution Epithermal Neutron Detector);

 

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Q1) What is NOMAD (Nadir and Occultation for MArs Discovery)?

(NOMAD) instrument is a spectrometer suite led by the Belgian Institute for Space Aeronomy (BIRA-IASB), being flown on the ESA/Roscosmos ExoMars Trace Gas Orbiter mission.NOMAD consists of three separate channels, Solar Occultation (SO), Limb Nadir and Occultation (LNO) and Ultraviolet and VIsible Spectrometer (UVIS), all controlled via a single main electronics unit (SINBAD).

Source: First contact: Alien signal beamed to Earth from Mars for the first time