Delta IV Heavy's US Spy Satellite Launch

Space.com

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

Transcript

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.

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