Proton Lifts Off on 15-hour Return to Flight Mission

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WASHINGTON — A Proton M rocket launched from the Baikonur Cosmodrome Aug. 28 on its first mission since a failed launch in May.

The Proton M lifted off from Baikonur at 7:44 a.m. Eastern time.

International Launch Services, Proton’s Reston, Va.-based commercial broker, reported that the rocket successfully completed the early phases of its mission, including the separation of its first three stages and the first of five scheduled burns of its Breeze M upper stage.

Any declaration of mission success, however, will have to wait until the Breeze M releases its payload, the Inmarsat-5 F3 satellite, into a super-synchronous transfer orbit. Spacecraft separation is scheduled for 15 hours and 31 minutes after liftoff.

The launch is the first for the Proton since the May 16 failure of a Proton rocket carrying Mexico’s Centenario satellite. Investigators blamed that failure on the “sup-optimal design” of a connection holding a steering engine turbopump on the rocket’s third stage. That caused the engine to fail a little more than eight minutes after liftoff.

Inmarsat-5 F3, a Boeing-built satellite weighing 6,070 kilograms at launch, is the third and final satellite in Inmarsat’s Global Xpress broadband satellite system. The satellite will serve the Pacific Ocean region.