In less than a minute, this speeded-up animation depicts the progress made by ExoMars Trace Gas Orbiter during its year-long aerobraking campaign at Mars, between January 2017 and March 2018. It shows the lowering of the apocentre (point of furthest separation from Mars) on each orbit, at right, owing to the slight drag imparted by the faint wisps of Mars’ upper atmosphere at pericentre (point of closest approach) on each orbit, at left.
The pause around the 20 second point corresponds to the pause in aerobraking in summer 2017 due to Mars conjunction, when the Sun, Earth and Mars lined up in their orbits, blocking reliable radio communication between the two planets.
The final orbit, approximately 380 x 420 km and almost circular, will be attained around mid-April. This orbit will be optimised for science observations for the spacecraft’s instruments and for catching signals from surface rovers for relay to Earth.