Video: NROL-37 payload and Delta 4-Heavy rocket prepped for launch

United Launch Alliance teams rolled the Mobile Service Tower away from a Delta 4-Heavy rocket at Cape Canaveral’s Complex 37B launch pad Wednesday in preparation for liftoff on a national security mission.

The fifth and final satellite for the U.S. Navy’s new mobile network to provide rugged smartphone communications to all branches of the military has arrived at the launch site for blastoff in May.

Ground crews at Vandenberg Air Force Base in California retracted a mobile gantry away from the Delta 2 rocket Monday afternoon, revealing the 128-foot-tall (39-meter) booster on its launch pad awaiting liftoff with a new polar-orbiting weather observatory.