ATK Provides Propulsion and Composite Structures for Successful Launch of IBEX Spacecraft on a Pegasus Rocket

Launch Marks Close to Two Decades of Successful Missions Using ATK Products

Alliant Techsystems (NYSE: ATK) supported the successful launch of an Orbital Sciences Corporation air-launched Pegasus XL(R) vehicle from the Ronald Reagan Ballistic Missile Defense Test Site from Kwajalein Atoll in the Pacific Ocean. The Pegasus was carrying the Interstellar Boundary Explorer (IBEX) spacecraft into space.

ATK provided propulsion for all three stages of the air-launched vehicle. ATK’s Orion motors — manufactured in Magna, Utah — have been used to successfully launch the Pegasus since its first mission in 1990. The Pegasus vehicle’s payload fairing, inter-stage raceways, and the filament-wound solid rocket motor cases were produced in Clearfield, Utah.

The IBEX spacecraft will utilize an ATK STAR 27H solid rocket motor to raise the initial 200 km orbit to a highly elliptical 7000 km by 50 Earth radii orbit. The STAR 27H motor is produced at ATK’s Elkton, MD facility. Once on orbit, the IBEX spacecraft will observe the heliosheath and termination shock of our solar system. This will be the first time these items have been photographed and studied.

ATK’s STAR motors have achieved many impressive feats in their four decades of use and more than 2400 successful flights. Not only have the STAR motors achieved the title of fastest human-made object, but they have been used on several of the world’s launch vehicles as well as the first orbit insertion around the moon and the first soft landing on the moon.

Pegasus is initially lifted to an altitude of 40,000 feet under an L-1011 aircraft, where it is released horizontally before the first-stage Orion 50 motor is ignited. Approximately 110 seconds into the flight, a composite payload fairing is jettisoned following the Orion 50 second-stage ignition. The third-stage Orion 38 motor burns until approximately 10 minutes into the flight, where the Pegasus delivers its payload into orbit. This mission represents the first four-stage version of Pegasus by incorporating a STAR motor to meet the high-energy requirements of the IBEX orbit.

Since its initial flight in 1990, the Pegasus rocket has now conducted 40 successful missions where more than 78 satellites and spacecraft have been delivered into orbit. Pegasus, along with ATK’s Orion motors, has set a standard for reliable small launch vehicles and motors. This launch was the 26th successful launch of the Pegasus vehicle.

ATK is a premier aerospace and defense company with more than 17,000 employees in 21 states and $4.5 billion in revenue. News and information can be found on the Internet at http://www.atk.com.

Certain information discussed in this press release constitutes forward- looking statements as defined in the Private Securities Litigation Reform Act of 1995. Although ATK believes that the expectations reflected in such forward-looking statements are based on reasonable assumptions, it can give no assurance that its expectations will be achieved. Forward-looking information is subject to certain risks, trends and uncertainties that could cause actual results to differ materially from those projected. Among those factors are: the challenges of developing next-generation human space launch vehicles; changes in governmental spending, budgetary policies and product sourcing strategies; the company’s competitive environment; the terms and timing of awards and contracts; and economic conditions. ATK undertakes no obligation to update any forward-looking statements. For further information on factors that could impact ATK, and statements contained herein, please refer to ATK’s most recent Annual Report on Form 10-K and any subsequent quarterly reports on Form 10-Q and current reports on Form 8-K filed with the U.S. Securities and Exchange Commission.