Waterside view of Delta 4 GPS 2F-6 Launch

United Launch Alliance engineers filled a Delta 4-Heavy rocket with super-cold liquid hydrogen and liquid oxygen propellants Friday at Cape Canaveral Air Force Station during a practice countdown before the heavy-lifter’s scheduled liftoff in June with a top secret U.S. government spy satellite.

The United Launch Alliance Delta 4 rocket, standing 206 feet tall and and weighing 720,000 pounds, unleashes 1.1 million pounds of thrust from its main engine and two side-mounted boosters at 12:52 a.m. EDT (0452 today to launch the GSSAP No. 3 and No. 4 satellites for the Geosynchronous Space Situational Awareness Program from Cape Canaveral.

A United Launch Delta 4 rocket lifted off Friday from the SLC-6 launch pad at Vandenberg Air Force Base in California, powering into orbit from a historic seaside complex originally developed for crewed missions.