'Most metal’ rocket from United Launch Alliance set to retire after this week's launch
When the ULA rocket engines ignite, the reaction with the hydrogen fuel causes flames to travel up the rocket boosters. For this reason, ULA has dubbed the Delta IV Heavy the “most metal of rockets."
Inaugural launch of ULA's Vulcan rocket
FILE VIDEO: ULA's Vulcan rocket launches for the first time carrying the Peregrine Moon lander to space. The liftoff happened from Cape Canaveral, Florida on Jan. 8. (video: ULA)
CAPE CANAVERAL SPACE FORCE STATION, Fla. – United Launch Alliance is preparing to bid farewell to the "most metal of rockets" with the final launch of the Delta IV Heavy.
After its 16th launch, ULA will retire the Delta IV Heavy from its fleet. The penultimate liftoff of the rocket happened in June, launching a National Reconnaissance Office (NRO) NROL-68 mission. The final Delta launch will also be a national security mission for the NRO.
ULA is targeting Thursday, March 28 at 1:40 p.m. ET to launch the NROL-70 payload into orbit from Launch Complex 37 at Cape Canaveral Space Force Station in Florida.
The Delta IV Heavy is a powerful bird to see fly.
The rocket has three side-by-side booster cores, each with Aerojet Rocketdyne RS-68A engines providing a combined 2.1 million pounds of thrust at liftoff. Four states contribute engineering, design, testing and parts for the rocket: Colorado, California, Alabama and Florida.

A United Launch Alliance (ULA) Delta IV Heavy rocket is transported from the Horizontal Integration Facility to Space Launch Complex-37 in preparation to launch the NROL-70 mission for the National Reconnaissance Office. Photo credit: United Launch Alliance
(ULA)
When the Delta rocket engines ignite, the reaction with the hydrogen fuel causes flames to travel up the rocket boosters, resulting in a fiery display. For this reason, ULA has dubbed the Delta IV Heavy the "most metal of rockets."
The Delta rocket series has been flying for more than 60 years.

United Launch Alliance Delta IV Heavy roars to life on the launchpad in Cape Canaveral, Florida on June 22, 2023. (Image credit: ULA)
(ULA)
ULA is replacing its workhorse rocket, the Atlas V, and the Delta Heavy with the new Vulcan rocket. The Atlas series uses Russian-made RD-180 engines. Vulcan uses American-made hardware, including Blue Origin and Aerojet Rocketdyne engines.
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The company’s inaugural Vulcan launch happened in January, launching Astrobotic’s robotic mission to the Moon. While Astrobotic’s mission did not ultimately reach the Moon, the lunar orbital assist from ULA went flawlessly, according to both companies.