'Sudden External Impact' Cripples Russian Satellite

PARIS - ARussian telecommunications satellite in geostationary orbit failed March 29following what its builder says was a "sudden external impact" of undetermined origin.The satellite, Express-AM11, is being moved into a graveyard orbit beforeon-board temperatures render it uncontrollable, the Russian SatelliteCommunications Co. (RSCC) announced March 30.

RSCC'sExpress-AM11 telecommunications spacecraft, launched in April 2004, isstationed at 96.5 degrees east longitude. The satellite, built by primecontractor NPO PM of Krasnoyarsk, Russia, with the electronics payload providedby Alcatel Alenia Space of France and Italy, carries 26 C-band and four Ku-bandtransponders. It was designed to operate for 12 years.

RSCC saidcommunications traffic that has Russian government priority has beentransferred to other RSCC spacecraft located at 80 degrees, 103 degrees and 140degrees east longitude. The company said most commercial traffic also has beentransferred to other spacecraft.

The failureoccurred suddenly at 3:41 a.m. Moscow time March 29, RSCC said in itsstatement.

"Accordingto the preliminary finding of NPO PM ... the telemetry information shows thatdue to a sudden external impact, an instantaneous depressurization of thethermal control system fluid circuit happened, followed by a sudden outburst ofthe heat-carrying agent. This resulted in ... spacecraft orientation loss androtation."

Oneindustry official said an external agent such as a micro-meteorite could havecaused a sudden rupture of the satellite's thermal-control piping, which in asevere case could result in a loss of spacecraft control. But this officialalso said NPO PM could conclude that an external factor was the cause in theabsence of any other explanation, and the absence of earlier signs of troubleon the spacecraft. While this conclusion would be reasonable, this officialsaid it would not eliminate the possibility that a soldered thermal-controlcircuit broke for other reasons.

RSCCspokeswoman Elena Polischuk said March 30 that the rupture of thethermal-control lines means the satellite's temperatures cannot be controlled,and that it must be moved soon to avoid becoming a menace to the geostationaryarc at 36,000 kilometers in altitude. RSCC ground teams currently have thesatellite under control, Polischuk said.

"In orderto prevent fatal consequences associated with space garbage formation ... whichwould result in the impossibility of using this orbital slot in future ...measures aimed at removing Express-AM11 from 96.5 degrees east into a disposalorbit have been taken," RSCC said.

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