A brief test-firing of a Falcon 9 rocket Wednesday morning kept SpaceX on track for a launch Saturday night from Cape Canaveral with a communications satellite to be jointly used by Telesat and APT Satellite of Hong Kong.

The United Launch Alliance Atlas 5 rocket, standing 194 feet tall and and weighing a million pounds, unleashes 1.6 million pounds of thrust from its main engine and two side-mounted solid boosters to launch the secret NROL-52 payload for the U.S. National Reconnaissance Office from Cape Canaveral.

Watch a replay of the Atlas 5 rocket soaring into space on 14 April carrying multiple U.S. Air Force communications and tech demo satellites.