Aerobraking progress
Date: 20 February 2018
Copyright: ESA/J. Bauer
In less than a minute, this speeded-up animation depicts the progress made by the ExoMars Trace Gas Orbiter as it used aerobraking to lower its orbit between March 2017 and February 2018, during the year-long aerobraking campaign at Mars.
The video 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 aerobraking concluded on 20 February, when the spacecraft fired its thrusters to raise the pericentre altitude to about 200 km, well out of the atmosphere, leaving the Trace gas Orbiter in an orbit of 1050 × 200 km.
The final orbit, approximately 380 × 420 km and almost circular, is highlighted in green and will be attained around mid-April, following a series of orbit-trimming manoeuvres using the spacecraft's thrusters. This orbit will be optimised for science observations for the spacecraft's instruments and for catching signals from surface rovers for relay to Earth.