ATK’S Orion Motors Provide the Propulsion Backbone for the Nation’s Ground- Based Missile Defense Program

Alliant Techsystems has received a $90 million contract to provide first, second, and third stage Orion solid rocket motors to Orbital Sciences Corporation (NYSE: ORB – News) for use in a variety of launch platforms including the nation’s Ground-based Missile Defense (GMD) program. ATK’s Launch Systems Group will perform the work at its manufacturing facilities in Utah. Production will run through February 2009.

ATK first produced Orion solid rocket motors in 1990 for Orbital’s Pegasus® launch vehicle, the first air-launched rocket to place satellites into orbit. Most recently, Orion motors were installed at Ft. Greely, Alaska and Vandenberg AFB, California. These reliable motors have proven their flexibility on multiple programs as they have been modified for use in a variety of launch vehicles, including Taurus®, Pegasus XL®, Minotaur®, and Hyper-X.

ATK is a $3.4 billion advanced weapon and space systems company employing approximately 15,000 people in 22 states. News and information can be found on the Internet at .

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: 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, reference should be made to ATK’s filings with the Securities and Exchange Commission, including quarterly reports on Form 10-Q, current reports on Form 8-K, and ATK’s Annual Report on Form 10-K for the fiscal year ended March 31, 2006.