Roscosmos Fingers Botched Sensor Installation in July 2 Proton Failure

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GLASGOW, Scotland — The spectacular July 2 failure of Russia’s Proton rocket just seconds after liftoff was probably caused by the botched installation of angular rate sensors on the rocket’s first stage, the Russian space agency, Roscosmos, said July 18.

The installation error would have accounted for the vehicle’s wild trajectory just after liftoff as it weaved from side to side before going horizontal, breaking up and bursting into flames.

In a statement, Roscosmos said the rocket’s liftoff at 0.4 seconds before the scheduled time is a subject of further review by the board of inquiry, but that this is not viewed as a likely contributor to the launch failure, which destroyed three Russian Glonass positioning, navigation and timing satellites. The statement confirmed that there were no injuries or major property damage resulting from the vehicle’s crash.

The statement appears to confirm earlier Russian press reports that investigators combing through the debris at the Baikonur Cosmodrome spaceport in Kazakhstan found evidence that several sensors were installed upside down. The Roscosmos statement said investigators found evidence that several of the sensors found at the crash site showed signs of a forced assembly, which would be consistent with their being installed at 180 degrees from their correct position.

The statement said Proton prime contractor Khrunichev State Research and Production Space Center did not have in place monitoring and review procedures that would have spotted the installation error.

The Russian state-led investigation is continuing, and Roscosmos gave no word on when Proton might be permitted to return to flight.

Owners of commercial satellites awaiting Proton launches managed by International Launch Services (ILS) of Reston, Va., have said in recent weeks that if the Proton failure were traced to an obvious manufacturing or integration flaw, the vehicle could return to commercial service this fall.

These officials’ confidence in a quick return to flight — which would need to be accepted by insurance underwriters providing coverage for commercial Proton launch contracts — was buoyed by the fact that commercial Proton launches have failed much less frequently than Russian government Proton missions in recent years.