The Delta 4 rocket lifted off from coastal Vandenberg Air Force Base at 2:11 p.m. Friday and headed toward orbit.
It marked the 27th NRO launch by United Launch Alliance, which is a Colorado-based aerospace partnership between Lockheed Martin and Boeing. "The forecast shows a 90% chance of favourable weather conditions for launch".
The vehicle will launch the classified NROL-47 payload for the U.S. National Reconnaissance Office. As usual with classified launchings, no details were provided about the satellite payload or its intended orbit. "My honest thanks to the entire ULA team and our mission partners at the NRO and U.S. Air Force who made this, our 27th NRO launch, possible".
The launch will happen at Space Launch Complex-6, which sits about 140 miles west of downtown Los Angeles.
A rocket carrying a spy satellite launched from Vandenberg Air Force Base Friday afternoon after being delayed a day due to technical issues.
The United Launch Alliance Delta IV rocket launches from Vandenberg Air Force Base on Friday afternoon
Orbital ATK provided two 60-inch diameter Graphite Epoxy Motors (GEM 60) for the Delta IV rocket.
Col. Greg Wood, 30th Space Wing vice commander, was the launch commander.
The GEM 60s provided additional thrust to the lone Aerojet Rocketdyne RS-68A engine located in the Delta IV's first stage.
This was the 36th flight of a ULA Delta 4 rocket and the first since last March. The RS-68A engine provided an estimated 702,000 pounds of thrust during the initial phase of the flight.
A ground system helium problem caused blastoff to be delayed by more than hour. "We are proud to provide this national defense capability, and every Team V member involved has tirelessly worked to ensure the launch is safe and successful". The commercially developed EELV program supports the full range of government mission requirements, while delivering on schedule and providing significant cost savings over the legacy launch systems.More news: Leaked Report Shows Trump Wants New 'Low-Yield Nukes'