The ExoMars Trace Gas Orbiter is a joint mission between the European Space Agency (ESA) and NASA.

Its aim is to investigate the different chemicals in the Martian atmosphere.

The Mars Express Orbiter discovered methane gas in the atmosphere of the red planet in 2003. On Earth, methane is given off by many animals and bacteria as a waste product, so scientists want to know if the methane on Mars is a sign of life.

“This allows us to investigate further that most important of questions: is Mars a living planet, and if not, can or will it become so in the future?” says the ESA’s David Southwood.