The ExoMars Trace Gas Orbiter (TGO or ExoMars Orbiter) is a collaborative project between the European Space Agency (ESA) and the Russian Roscosmos agency that sent an atmospheric research orbiter and the Schiaparelli demonstration lander to Mars in 2016 as part of the European-led ExoMars programme. A key goal is to gain a better understanding of methane (CH4) and other trace gases present in the Martian atmosphere that could be evidence for possible biological activity. Manufactured by Thales Alenia Space, TGO's major scientific payloads were developed by Belgium, France, Russia, and Switzerland. TGO launched on a Proton-M rocket from Baikonur Cosmodrome Site 200, in Kazakhstan, on 14 March 2016.

Wikipedia: https://en.wikipedia.org/wiki/ExoMars_Trace_Gas_Orbiter. Original timeline Wikipedia link: https://en.wikipedia.org/wiki/ExoMars. Related NASA reference: https://nssdc.gsfc.nasa.gov/planetary/chronology.html#2016. Description adapted from Wikipedia contributors (CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/).