United Launch Alliance, headquartered in Denver, is a joint venture of Lockheed Martin and the Boeing Co.
There's an 80 percent chance of favorable weather for the Friday afternoon launch, United Launch Alliance said on Twitter.
The launch, NROL-47, will mark ULA's 27th mission for the National Reconnaissance Office. "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 government hasn't confirmed whether the top-secret satellite did indeed fall out of orbit and reenter Earth's atmosphere. "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". However, this was not the only variable thrown at the launch team with an issue with a ground system valve forcing mission managers to call a scrub for the Thursday, Jan. 11 launch attempt (s) as well.
Orbital ATK provided two 60-inch diameter Graphite Epoxy Motors (GEM 60) for the Delta IV rocket.
"We are ready and eager to take on this Delta launch", Col. Greg Wood, launch commander and vice commander of the Air Force's 30th Space Wing, said in a statement earlier this week. The rocket is a "5, 2" variant and it featured a 5-meter-wide (16.5 feet) payload fairing, as reported by Space.com.
The blastoff and initial phases of the rocket's flight were a success. The booster and upper stage engines are both built by Aerojet Rocketdyne. The RS-68A engine provided an estimated 702,000 pounds of thrust during the initial phase of the flight.
The launch was then delayed by about an hour due to a ground system helium issue. Established by the U.S. Air Force, the EELV program provides assured access to space for Department of Defense and other government agencies.
Sunday's launch was SpaceX's third classified mission.