Alliant Techsystems said its propulsion and composite technologies supported the successful launch Tuesday evening of a Boeing Delta IV rocket carrying a classified spy satellite for the U.S. National Reconnaissance Office.
The mission was the first for the Delta IV launched from the Western Range at Vandenberg Air Force Base, Calif.
ATK Launch Systems designed and produced the nozzle for the Pratt & Whitney Rocketdyne-built RS-68 engine, as well as the nozzle's thermal protection material, capable of shielding it from the extreme heat of launch, where external temperatures can exceed 4,000 degrees Fahrenheit.
The Delta IV's RS-68 is the largest hydrogen-fueled rocket engine in the world, utilizing an ATK nozzle that is the first of its kind in a liquid booster engine.
Two GEM-60 solid propulsion strap-on boosters, also built by ATK, provided augmented thrust for the launch. The two 60-inch-diameter boosters ignited at liftoff and burned for just over 90 seconds, ATK reported in a news release. Then the boosters were jettisoned from the common booster core and fell back to Earth.
During the flight, each GEM provided 195,000 pounds of average thrust.
ATK also supplied five composite structures for the Delta IV:
– the thermal shielding that houses the RS-68 main engine;
– the center body that connects the liquid oxygen and hydrogen tanks;
– the liquid oxygen forward skirt that connects with the interstage and interfaces the 5-meter-diameter common booster core with the 4-meter-diameter upper stage and payload;
– the payload-attach fitting and diaphragm that interface the upper stage with the payload, and
– the fairing that houses the rocket's payload.
