The NROL-47 launch was scheduled for January 10th, but it was scrapped because of high ground winds. Beginning in 2019, Orbital ATK will provide upgraded GEM 60 solid rocket boosters, designated GEM 63 and GEM 63XL, for ULA's Atlas V and new Vulcan launch vehicles, respectively.
ULA's webcast launch commentator did not mention the satellite beyond its name and as usual for classified missions, the company ended its coverage after payload fairing jettison.
The 32-story-tall mobile service tower at the Delta 4's launch pad at Vandenberg Air Force Base in California was retracted away from the rocket Thursday in advance of a planned liftoff with a top secret National Reconnaissance Office payload.
The office is in charge of designing, building, launching and maintaining US intelligence satellites.
The launch provider United Launch Alliance (ULA) subsequently delayed it by 24 hours. The NRO publicized the launch with generic tweets, saying the mission was the first of two planned by the agency this year.
Colonel Greg Wood, 30th Space Wing vice commander, said: "We are ready and eager to take on this Delta launch".
The GEM 60s provided additional thrust to the lone Aerojet Rocketdyne RS-68A engine located in the Delta IV's first stage. After staging, an Aerojet Rocketdyne RL10B-2 granted some 24,750 pounds of thrust, sending the Delta IV's upper stage to orbit.
"It's a national security payload and this mission will ensure the warfighters across the globe have the appropriate intel that they need to support operations", said Maj.
The same policy was in place last Sunday when SpaceX launched a classified satellite known as Zuma atop a Falcon 9 rocket from Cape Canaveral. Jim began blogging about science, science fiction and futurism in 2004.