Trace_Gas_Orbiter_at_Mars
Artist’s impression of the ExoMars 2016 Trace Gas Orbiter at Mars. ESA/ATG medialab

The European Space Agency (ESA) announced Tuesday it had, over the course of three engine burns last month, adjusted the orbit of its ExoMars Trace Gas Orbiter (TGO), moving it closer to its final one. The maneuvers raise the spacecraft’s orbit from equatorial to a more north–south one.

“The three firings shifted its angle of travel with respect to the equator to almost 74 degrees from the 7 degrees of its October arrival. This essentially raised the orbit from equatorial to being much more north–south,” the ESA said in a statement.

The orbital maneuvers were needed to ensure optimum coverage of the surface for the instruments on board the TGO, and to eventually bring the spacecraft to its-near circular science orbit, which would have an altitude of roughly 250 miles.

The TGO’s current elliptical orbit brings the spacecraft just 130 miles above the surface of the red planet during closest approach.

ExoMars_Angle_change
This image indicates the angle of TGO’s orbit before and after the orbital inclination change manoeuvres in 2017. Upon arrival, in October 2016, the orbit, at about 7º, was essentially equatorial – indicated by the horizontal orbital lines in the graphic. After the manoeuvres in January and February 2017, the orbit was oriented much more north-south, at about 74º, indicated by the almost-vertical orbital lines. In the image, Mars’ north pole is at the top, the south pole is at the bottom and the equator is horizontal. ESA/C. Carreau

“The manoeuvres were performed using the main engine in three steps to avoid a possible situation where the spacecraft could end up on a collision course with Mars in case of any unexpected early termination or underperformance of the engine,” Peter Schmitz, the spacecraft operations manager, said in the statement. “All three [engine burns] were completed to within just a few tenths of a percent of the target thrust, resulting in the craft’s orbital plane being off by just a few fractions of a degree, which is trivial.”

Much before its main science mission begins next year, the ExoMars science team would have another opportunity to gather crucial data in March, when the TGO’s science instruments would be switched on. Data gathered during the orbit would add to that gathered during two dedicated science orbits late last year.

The ExoMars spacecraft, launched in March 2016, originally consisted of two parts — the TGO, and the Schiaparelli Entry, Descent and Landing demonstrator module. In October, after a seven-month journey, the TGO successfully inserted itself into an orbit around the Mars, but the lander, which was supposed to make a soft landing on the surface, failed to beam back signals that would have shown it had done so successfully.

The main objective of the ExoMars mission is to search for evidence of methane — a gas emitted by living microbes on Earth, and traces of which have been observed by previous Mars missions — and other trace atmospheric gases that could be signatures of active biological or geological processes.

In addition, the TGO would also serve as a data relay for the ExoMars 2020 mission, which would consist of a rover and a surface platform. While the solar-powered rover will perambulate the rocky terrain of Mars, drill through the surface to collect samples, and look for signs of organic material and the possibility of life — extant or extinct. — the surface platform will, over the course of one Earth year, investigate the environment at the landing site.

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