ULA Delta IV Heavy Rocket Launches From Vandenberg Air Force Base [WATCH]

A new US spy satellite was launched into orbit on the United Launch Alliance's (ULA) most powerful launcher, the giant Delta IV Heavy, on Monday afternoon (April 26).

The behemoth launched from Space Launch Complex 6 at Vandenberg Air Force Base in California at 4:47 p.m. EST. It brought the classified NROL-82 satellite into orbit for the National Reconnaissance Office (NRO).

NASA Prepares For Orion Test Launch — CAPE CANAVERAL, FL - DECEMBER 03: In this handout provided by National Aeronautics and Space Administration (NASA), the United Launch Alliance Delta 4 rocket carrying NASA's first Orion deep space exploration craft is seen at Cape Canaveral Air Force Station's Space Launch Complex 37, December 3, 2014 in Cape Canaveral, Florida. The heavy-lift rocket is prepared for a 7:05 launch tomorrow morning and it will boost the unmanned Orion capsule to an altitude of 3,600 miles, and returning for a splashdown west of Baja California after a four and half hour flight. Bill Ingalls/NASA via Getty Images

During a webcast of the launch, launch commentator Caroline Kirk said Delta IV engineer Rob Kesselman "confirmed the successful completion of the early phase of today's flight." He added that all systems continue to work nominally.

Just four Delta IV Heavy rockets remain in ULA's fleet, a 50-50 joint venture between Lockheed Martin and Boeing. All of them have been assigned to launch NRO missions. Two of them are launching from California (including today's mission) and the other two from Florida.

About Delta IV Heavy

The Delta IV Heavy is ULA's most powerful rocket at the moment. The mega launcher comprises three common core boosters that produce over 2 million pounds of thrust. These are powered by 465,000 gallons (1.76 million liters) of superchilled liquid hydrogen and liquid oxygen.

The Delta II and Delta IV Medium were single-stick versions of the Delta family of rockets. Space.com said ULA previously retired the Delta II and Delta IV Medium rockets in 2018 and 2019, respectively).

Monday's launch was the 13th for a Delta IV Heavy rocket since its debut in 2004, and one of only four remaining Delta IV rockets. ULA intends to withdraw the launcher before introducing the Vulcan Centaur, its next-generation vehicle. The launcher is expected to be released later this year.

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The 330-foot-tall (100-meter) shroud encasing the rocket, known as the Mobile Service Tower (MST) rolled away shortly before the launch countdown began. It revealed the gigantic spacecraft, which stands 233 feet (71 meters) tall and measures approximately 53 feet (16 meters).

NRO payloads were carried on eight of the previous 12 Delta IV Heavy missions. Other notable missions of the vehicle include NASA's Orion capsule's uncrewed test flight to Earth orbit in 2014 and the Parker Solar Probe's attempt to examine the sun.

The rocket was lifted on the pad at SLC-6 in February as part of the launch preparations. Since then, the team has conducted a wet dress rehearsal, in which they loaded the rocket with fuel and practiced launch procedures to ensure that all of the rocket's systems are operational.

The payload was mounted atop the rocket earlier this month. This was the ninth Delta IV mission to launch from SLC-6, which was originally designed to launch space shuttles from the West Coast.

ULA's first flight of 2021 was the NROL-82 mission. Suppose the remainder of the company's launch schedule goes according to plan, it will be able to complete as many as 10 missions before the end of the year. ULA is scheduled to fly six times in 2020, including the Mars Perseverance rover.

After the Delta is retired, ULA plans to launch future national security missions with its forthcoming Vulcan Centaur rocket, which is expected to launch later this year.