Posted by Courtney Howard
MINNEAPOLIS, 8 Dec. 2009. Alliant Techsystems' composite, propulsion, and spacecraft technologies supported the launch of a United Launch Alliance Delta IV rocket from Space Launch Complex 37 at Cape Canaveral Air Force Station, Fla., carrying the Wideband Global SATCOM (WGS-3) for the U.S. Air Force.
The Delta IV medium-plus rocket featured four ATK 60-inch-diameter Graphite Epoxy Motors (GEM), the composite cases of which were fabricated at the ATK Clearfield, Utah facility. The 70-foot-long motors--mounted in pairs on opposite sides of the rocket and including one fixed and one vectorable nozzle per side--provided auxiliary lift-off capability for the Delta IV. The GEM 60s burned for 90 seconds, delivering 1,120,000 pounds of thrust to launch the WGS satellite into orbit.
ATK also designed and produced the nozzle for the Delta IV's RS-68 engine. The Pratt & Whitney Rocketdyne-built RS-68 is the largest hydrogen-fueled engine in the world, reveals a company representative. Further, ATK designed and developed the nozzle's thermal protection material, capable of shielding the nozzle from the extreme heat of launch when external temperatures can exceed 4,000 degrees F. The nozzle is manufactured at ATK's Promontory, Utah facility.
"ATK supplied 10 key composite structures for the Delta IV medium-plus launch vehicle: the interstage that provides the interface between the Common Booster Core (CBC) and the cryogenic second stage, a centerbody that integrates the liquid oxygen (LO2) and liquid hydrogen (LH2) tanks, a thermal shield that protects the RS-68 engine during ignition and flight, one LO2 skirt, and one aeroskirt," explains a company official. The payload is encapsulated by ATK's 5-meter diameter composite payload fairing, along with required hardware for payload integration including a nose cap, x-panels, payload attach fitting, and payload attach fitting diaphragm.
ATK delivered electronics subsystems for the launch. ATK's Commerce, Calif. facility provided the propellant tank for the Delta IV upper stage roll control system. ATK Space Structures based in San Diego manufactured the payload module and the solar array substrates panels.
WGS-3, the third satellite of the series, is designed to provide high-capacity, X-band and Ka-band communications support to the U.S. and allied air forces in military operations across the world.
WGS-1 has been in operation over the Pacific since April 2008, and WGS-2 has been operating over the Middle East since August 2009.
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