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ESA experts try to establish communication with Phobos-Grunt

November 25, 2011, 12:25 UTC+3
Working with Russian mission controllers, ESA engineers are carefully studying the situation, which may be related to the spacecraft's communication system
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MOSCOW, November 25 (Itar-Tass) — Specialists of the European Space Agency (ESA), working at the Perth tracking station (Australia) overnight made four attempts at establishing communication with the Phobos-Grunt (Phobos-Soil) automatic interplanetary station.

“All the four attempts proved futile,” head of the ESA office in Moscow Rene Pichel told Itar-Tass on Friday. “On Friday afternoon, specialists of the ESA and the NPO Lavochkin research and production association are to outline the work plan for this night,” he specified.

It was previously planned that on the night from November 24 to 25 the Perth tracking station would hold five communication sessions with the automatic interplanetary station, including will try to transfer control commands to the station.

According to the ESA, following the first successful contact on Tuesday, ESA’s tracking station in Australia again established two-way communication with Russia’s Phobos-Grunt spacecraft on 23 November. The data received from the spacecraft have been sent to the Russian mission control centre for analysis. ESA’s 15 m-diameter antenna at Perth, Australia, was again used to contact Russia’s Phobos– Grunt spacecraft during the night of 23–24 November, with a total of five communication passes available between 20:19 and 04:08 GMT. Teams working at the Perth station and at ESA’s Space Operations Centre, Darmstadt, Germany, were delighted to see a clear signal during the first of the passes.

“The first pass was successful in that the spacecraft’s radio downlink was commanded to switch on and telemetry was received," said Wolfgang Hell, ESA’s Service Manager for Phobos-Grunt. Telemetry typically includes information on the status and health of a spacecraft’s systems. “The signals received from Phobos-Grunt were much stronger than those initially received on 22 November, in part due to having better knowledge of the spacecraft's orbital position.”

The second pass was short, and so was used only to uplink commands – no receipt of signal was expected. However, the following three passes in the early morning of 24 November proved to be more difficult: no signal was received from Phobos-Grunt, ESA reported.

Working with Russian mission controllers, ESA engineers are carefully studying the situation, which may be related to the spacecraft's communication system. During last night's first two passes, one of the two low-gain antennas on Phobos-Grunt was, due to the spacecraft's orbital position, oriented toward Perth, and communications worked, the agency reported.

During the three later passes, the spacecraft's orbital position changed, and the second, opposing, antenna had to be used – but no signal was received. “Our Russian colleagues will use this result for troubleshooting and to plan their commands for us to send tonight,” says Manfred Warhaut, ESA’s Head of Mission Operations.

ESA engineers will work to provide advice and assistance on possible communication strategies to consolidate the contact now established with the mission. Another five communication slots are available during the night of 24–25 November, and the Perth tracking station will again be allocated on a priority basis to Phobos-Grunt, according to the agency.

The launch of the Phobos-Grunt station was carried out from the Baikonur Cosmodrome November 9 by the Zenit-2SB launch vehicle. The station reached a low-Earth orbit from which it was to be transferred to an escape trajectory from Earth to Mars by two ignitions of its main propulsion system. For unknown reasons, the control system has failed to give the command to the first ignition of the propulsion system.

According to previously available data, since the launch time the station’s orbit has not degraded in height. This is possibly owing to the work of the Sun orientation subsystem that has given relevant commands to the low-thrust engines of the station that maintained the orbit’s altitude.

Initially, all the attempts to establish communication with the station were unsuccessful. The situation has begun to change since November 23 when first experts of the European Space Agency and then a Baikonur tracking station managed to temporarily restore contact with the station. Experts of the ESA and the Russian Federal Space Agency (Roskosmos) were preparing a program of further work with the automatic interplanetary station. They have little time left - as the window for Phobos-Grunt to enter the escape trajectory to Mars will be closed by the end November. It is before this date - November 26 – that the United States scheduled for launch the Atlas 5 carrier rocket, which should deliver to the Red Planet a new Mars rover named Curiosity.


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