Video: SpaceX test-fires Falcon 9 rocket at pad 40 (members only)

SpaceX’s next Falcon 9 rocket ignited its Merlin main engines for several seconds Thursday at Kennedy Space Center’s pad 39A ahead of a planned launch next week.

A replay of the United Launch Alliance Atlas 5 rocket launching the Orbital ATK’s commercial Cygnus cargo freighter to the International Space Station from Cape Canaveral, Florida.

United Launch Alliance called off the planned liftoff of a Delta 4-Heavy rocket and a classified National Reconnaissance Office spy satellite from Vandenberg Air Force Base in California on Wednesday after indications of elevated hydrogen concentrations around one of the launcher’s main engines. Three previous launch attempts were scrubbed by technical concerns and bad weather.