Live coverage: Ariane 5 rocket soars with Sky Muster, Arsat 2

A Russian Proton rocket launched at 0345 GMT Thursday (11:45 p.m. EDT Wednesday) from the Baikonur Cosmodrome in Kazakhstan with the EchoStar 21 communications satellite, a hefty 7.6-ton telecommunications station designed to support a mobile network in Europe. Managed by U.S.-based International Launch Services, the mission will take more than nine hours to deliver EchoStar 21 into a geostationary transfer orbit using five burns of the Breeze M upper stage engine.

An electrical problem on one of the Ariane 5 rocket’s two solid rocket boosters led to an on-pad launch abort Tuesday, likely delaying liftoff with two U.S.-built communications satellites until around the end of September, Arianespace officials said.

The next flight of an Ariane 5 rocket, previously set for next week, has been delayed to no earlier than July 30 to review the readiness components it has in common with the Vega rocket after a launch failure earlier this month.