LOS ANGELES, Calif., Sept. 24, 2022 – Aerojet Rocketdyne provided all of the thrust needed to power the successful launch of a United Launch Alliance (ULA) Delta IV Heavy rocket carrying a classified payload for the U.S. National Reconnaissance Office. This was the final scheduled launch of a Delta IV Heavy launch vehicle from Vandenberg Space Force Base in California.

“Delta IV rockets have been used to launch America’s high-value, national security payloads to orbit for nearly two decades,” said Aerojet Rocketdyne Senior Vice President of Space, Jim Maser. “ULA puts its trust in our reliable and flight proven RS-68 and RL10 propulsion systems, which have delivered 100% mission success since the program’s inception.”

The mission, known as NROL-91, blasted off at 3:25 p.m. local time from Space Launch Complex 6 at Vandenberg Space Force Base. The two Delta IV Heavy missions remaining on the launch manifest are both slated to launch from Cape Canaveral Space Force Station in Florida.

The Delta IV Heavy features three core stages in a side-by-side configuration, each powered by a single Aerojet Rocketdyne RS-68A engine that generates 705,000 pounds of thrust at liftoff. The RS-68A was developed specifically for the Delta IV and remains as the world’s most powerful hydrogen-fueled rocket engine to this day.

The vehicle’s second stage is powered by a single RL10C-2-1 hydrogen-fueled engine generating 24,750 pounds of thrust. Variants of the RL10 have been helping to power different launch vehicles since the 1960s and have sent spacecraft to explore every planet in our solar system. The second stage is also equipped with 12 Aerojet Rocketdyne MR-106 thrusters that provide roll, pitch and yaw control of the vehicle.

Operation of the Delta IV Heavy launch vehicle is also supported by 14 pressurant tanks built by Aerojet Rocketdyne subsidiary ARDÉ.