ULA Launches Final Delta Rocket After 64 Years

After 64 years of service, ULA on Tuesday launched its last-ever Delta rocket carrying a classified payload for the U.S. National Reconnaissance Office (NRO). "The powerful booster departed Space Launch Complex-37 (SLC-37) at Cape Canaveral Space Force Station in Florida at 12:53 p.m. EDT (1653 GMT), literally setting itself on fire for the 16th and final time," reports Space.com. From the report: That spectacle, which was unique to the Delta IV in its heaviest configuration, was the result of hydrogen building up in the flame trench and then rising up alongside the rocket after it was used to cool down the three RS-68A engines to cryogenic temperatures. When the engines fired, the hydrogen ignited and flames lapped at the orange insulation covering the core stage and its two side-mounted boosters. The two boosters were jettisoned about four minutes into the flight, followed by the core, or first stage, separating one minute and 45 seconds later. A single RL10C-2-1 engine on the Delta cryogenic second stage then took over, propelling the NROL-70 payload into space. Due to national security concerns, coverage of the launch ceased following fairing jettison at about 6 minutes and 40 seconds into the flight. ULA is retiring the Delta IV, and eventually its other legacy rocket, the Atlas V, in favor of its newly introduced Vulcan, which flew a near-perfect first mission in January. The Vulcan was developed to replace both long-flying rockets in all of their configurations. "This is a great mission to think about that transition, because national security space missions is our core and the unique set of missions there require a high-energy launch vehicle. We designed Vulcan specifically for that," said [Tory Bruno, chief executive officer of United Launch Alliance]. In addition to being the 16th Delta IV Heavy, Tuesday's launch was also the 45th liftoff of a Delta IV, the 35th Delta IV to fly from Florida and the 389th Delta launch of any kind since 1960 (of which 294 were sent skyward from Cape Canaveral). Half of the Delta IV Heavy launches were devoted to sending NRO payloads into orbit. The rocket and its less powerful configurations were also used in support of NASA, NOAA (the U.S. National Oceanic and Atmospheric Administration), U.S. Air Force and commercial payloads.

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