spacetoday.net: Proton launch anomaly blamed on turbopump bearing

Posted: Wed, Feb 13, 2013, 7:47 AM ET (1247 GMT)
Investigators have blamed a turbopump bearing failure for the premature shutdown of a Proton upper stage in December, International Launch Services (ILS) announced Tuesday. The company said "a combination of adverse conditions", not specified in the release, damaged a bearing in the oxidizer side of the turbopump powering the engine in the Briz-M upper stage. That bearing failed during the fourth engine burn of the upper stage, shutting the engine down several minutes early and leaving the rocket's payload, the Yamal-402 satellite, in a lower-than-planned transfer orbit. Engineers were able to maneuver the spacecraft to geosynchronous orbit using its own thrusters. The completion of the investigation clears the way for the Proton to return to commercial service with the launch of the Satmex 8 satellite in March.