ExoMars set for Mars rendezvous after communications failure

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The Schiaparelli demonstrator has separated from the Trace Gas Orbiter and is on a ballistic course for Mars(Credit: ESA)

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The ExoMars 2016 mission is set for its rendezvous with the Red Planet on October 19. On Sunday at 4:42 pm CEST (14:42 GMT), the Schiaparelli module successfully separated from the Trace Gas Orbiter (TGO), and Monday morning at 4:42 am CEST (02:42 GMT) the orbiter executed a crucial course correction after a heart-stopping glitch that caused the spacecraft to lose communications with Earth. Despite this, ESA says both the TGO and Schiaparelli are currently healthy and on course.

On October 16 at 10:10 am CEST (08:10 GMT), the dormant Schiaparelli was switched on and its systems examined one final time, with mission control in Darmstadt, Germany reporting telemetry indicated the spacecraft's temperature was normal. After a final check of the time-tagged commands that will guide it to the martian surface, Schiaparelli was automatically jettisoned by its mother ship on schedule at a speed of 30 cm/s (one ft/s), setting it on a three-day ballistic trajectory that will end in a dramatic six-minute descent.

During the separation maneuver, the TGO rotated to put it into the correct attitude. Since this swung its antenna momentarily out of line with Earth, the full data link was lost as expected and progress was monitored using the Giant Metrewave Radio Telescope (GMRT) radio telescope in Pune, India.

Because it takes almost 10 minutes for a radio signal to reach ExoMars from Earth, all operations by the TGO and Schiaparelli had to be carried out autonomously with mission control acting as little more than a spectator. Separation was confirmed by the Flight Director at 5:27 pm CEST (15:27 GMT), but instead of the telemetry signal returning, only the radio carrier wave came from the TGO.

Though ESA downplayed the significance of this, the TGO was within hours of a crucial engine burn that would cause it to swing around Mars. If a system failure prevented it from carrying out the maneuver, then the orbiter would follow Schiaparelli and, lacking a heat shield or parachutes, hit the Martian atmosphere at tremendous speed.

Fortunately, at 6:43 CEST (16:43 GMT) telemetry returned for reasons as unknown as those behind the blackout, with the first data recovered by ESA's 35-m (113-ft) deep-space ground station at Malargüe, Argentina.

On Monday at 4:42 am CEST (02:42 GMT), the TGO fired its main engine for one minute and 46 seconds to boost its trajectory by several hundred kilometers, which places the craft in its orbit insertion window. On Wednesday, the TGO will fire its engine for another 139 minutes to place it in orbit around Mars. To make certain that this burn is carried out without interruption, mission control ordered the probe to disregard any automatic computer reboot commands on Monday.

Meanwhile, Schiaparelli has gone back to sleep to conserve battery power. When it wakes up on Wednesday, it will plunge into the Martian atmosphere and after a six-minute braking maneuver land (hopefully) in the Meridiani Planum region near the equator at 4:48 pm CEST (14:48 GMT).

The video below previews the ExoMars orbit insertion and landings.

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