Photos: Tuesday’s Atlas 5 rollout

United Launch Alliance called off the planned launch of an Atlas 5 rocket Wednesday at Cape Canaveral to resolve a problem with valves at the launch pad, while a SpaceX team a mile-and-a-half to the south readied a Falcon 9 rocket for liftoff Thursday evening with a GPS navigation satellite for the U.S. military.

Two months after a first test-firing ended prematurely, NASA plans to ignite the core stage of the first Space Launch System heavy-lift rocket again Thursday for an eight-minute burn to confirm it is ready for shipment to the Kennedy Space Center for launch preparations.

China’s Long March 3B rocket, used to power navigation and communications satellites into high-altitude orbits, launched for the first time in nearly five months Sunday with two spacecraft for the country’s Beidou positioning network.