ATK composites figure prominently in Delta II launch

Carbon fiber/epoxy composites and the filament winding process are used to produce cases for the boosters.

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Alliant Techsystems (ATK, Minneapolis, Minn., USA) reported on May 6 that its propulsion, composites and spacecraft technologies played key roles in the successful launch of United Launch Alliance's Delta II rocket from Vandenberg Air Force Base in California, and the mission of the Missile Defense Agency's Space Tracking and Surveillance System - Advanced Technology Risk Reduction (STSS-ATRR) satellite.

ATK designed, fabricated, and tested the Optical Bench for the satellite deployed on this mission. The ATK bench is a critical composite structural assembly providing the required stability for the payload sensors onboard the spacecraft. ATK also provided engineering analysis for the precise thermal and moisture distortion performance of the payload bench required to meet mission expectations in the harsh environment of space.

The Missile Defense Agency's STSS Advanced Technology Risk Reduction satellite serves as a technology pathfinder for the STSS mission - a space-based sensor component of the layered Ballistic Missile Defense System.

Nine ATK GEM-40 solid propulsion strap-on boosters provided augmented thrust for the launch. Six of the boosters ignited at lift-off with the first-stage main engine and provided more than 824,000 lb maximum thrust. Just over one minute later, the remaining three boosters ignited to provide an additional 427,000 lb maximum thrust. The spent motors were then jettisoned from the rocket as it continued its ascent.

ATK manufactured the GEM-40 motors at its facility in Magna, Utah, continuing a tradition of flight support for Delta II missions that began in 1990. The composite cases for the GEM-40 boosters were produced at ATK's Clearfield, Utah, facility and are made of carbon fiber/epoxy composites using an automated filament winding process the company developed and refined through its 40-year heritage in composite manufacturing. The 10-foot/3.1m-diameter composite payload fairing, encapsulating the third stage that holds the payload, was fabricated by ATK's Iuka, Miss. facility. The fairing was produced using advanced composite hand layup manufacturing, machining and inspection techniques. This launch marks the 16th ATK-built fairing flown on a Delta II mission.