United Launch Alliances Delta Heavy IV rocket launch from Space Launch Complex-37 at Cape Canaveral Space Force Station in Florida for the final time. The rocket carries the NROL-70 mission for the National Reconnaissance Office.
Credit: ULA
Credit: ULA
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TechTranscript
00:00To mitigate the fireball created by the hydrogen-burning Delta IV Heavy rocket,
00:08the staggered engine start sequence begins with ignition of the launch table HBOs,
00:13burning off the excess hydrogen injected into the flame duct.
00:16Next, the starboard Delta IV roving lights, igniting its RS-68A engine.
00:24Then, the center and port RS-68A engines ignite,
00:28generate more than 2.1 million pounds of total thrust,
00:31to lift the 1.6 million pound triple core rocket off the pad.
00:40Shortly after liftoff, Delta begins a pitch over to attain the proper flight path,
00:44while minimizing the pressure the vehicle experiences during flight.
00:49Delta then reaches Mach 1, the speed of sound,
00:52followed by the rocket reaching maximum dynamic pressure as it travels through Earth's atmosphere.
01:01With propellant depleted in the port and starboard boosters,
01:04the engines shut down and the boosters jettison to shed their weight.
01:08The remaining booster engine then throttles to full power,
01:11to maximize performance against gravity losses.
01:16Once propellant levels deplete in the center booster,
01:18the engine shuts down and the booster is jettisoned from the second stage.
01:23The vehicle now weighs approximately 6% of what it did at liftoff.
01:30Following jettison of the center booster,
01:32the Delta Cryogenic Second Stage, or DCSS, main engine ignites.
01:38During ascent, NROL-70 is protected inside a 5-meter diameter metallic payload fairing.
01:45After traveling through the densest part of Earth's atmosphere, the payload fairing is jettisoned.
01:50The Delta IV Cryogenic Second Stage carries the last payload to launch on a Delta IV rocket
01:57to its final orbital destination, where it will begin its national security mission.