Live coverage: Two satellites lift off aboard Ariane 5

A powerful Russian Proton booster launched from Kazakhstan at 0931:42 GMT (5:31:42 a.m. EDT) Monday with the first part of a multibillion-dollar Mars mission led by the European Space Agency. An upper stage engine fired four times over 10 hours to send the Mars orbiter and lander away from Earth.

Two U.S.-built commercial communications satellites moved to their last stop on Earth on Tuesday, when an Ariane 5 rocket rolled out to a launch pad at the edge of the Amazon jungle on the eve of liftoff.

Arianespace has postponed this week’s launch of an Ariane 5 rocket with two European communications satellites to replace a faulty fluid connector between the launcher and its mobile launch platform, officials said Tuesday.