Live coverage: Ariane 5 blasts off with two Intelsat satellites

Passing a major pre-flight milestone ahead of a launch and landing planned early Sunday, a SpaceX Falcon 9 rocket ignited its main engines Wednesday for a hold-down firing at Cape Canaveral.

Arianespace plans to launch an Ariane 5 rocket from French Guiana on Sunday after fixing a disconnected helium vent line that required the launcher be returned to a hangar for repairs.

NASA is moving forward with a crucial test-firing of the core stage of the first Space Launch System heavy-lift rocket as soon as Jan. 17 after engineers were satisfied with the results of a fueling test last month.