Photos: More Launch shots of Delta 375 rocket

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.

Rocket Lab’s light-class Electron launcher is set to take off on its fifth flight from New Zealand, aiming for a 264-mile-high (425-kilometer) orbit with DARPA’s R3D2 technology demonstration satellite.

A test-firing of a twice-flown Falcon 9 booster Friday at Cape Canaveral paved the way for SpaceX’s next launch, scheduled for Monday night with a heavyweight Boeing-built communications satellite to beam broadband signals to Japan and the Pacific islands.