ExoMars first year in orbit

An overview animation of the ExoMars Trace Gas Orbiter’s expected path around Mars between October 2016 and December 2017.

The spacecraft entered orbit on 19 October 2016, on a highly elliptical path that took it between about 250 km and 98 000 km from the planet in about 4.2 days.

The main science mission is intended to take place from a near-circular 400 km orbit, starting in early 2018. The spacecraft will achieve this orbit by aerobraking – using the planet’s atmosphere to slow down gradually.

First, on 19 January 2017, the angle of the orbit will be changed to 74º with respect to the equator, so that science observations can cover most of the planet.

Next, to get into an aerobraking orbit, the craft will fire its thrusters in early February to reach 200 x 33 475 km, which will also reduce its orbital period to 24 hours.

Aerobraking is planned to begin on 15 March, with a series of seven manoeuvres – about one every three days – that will steadily lower the craft’s altitude at its point of closest approach, from 200 km to about 114 km. Then the atmosphere will take over, gradually reducing the most distant part of the orbit.

Final manoeuvres are expected at the end of 2017 to circularise the orbit at an altitude of about 400 km, whereupon the science mission can begin.

The animation is based on data available as of end-2016, but the actual timing of the various manoeuvres may be subject to change as operational plans develop during 2017.