Alliant Techsystems’ reusable solid rocket motors (RSRM) performed flawlessly today, providing more than six million pounds of thrust as NASA’s Space Shuttle Atlantis launched into orbit to begin a 11-day mission to the International Space Station (ISS) to continue installation of two additional solar panels.

During the STS-117 mission the crew will install the second and third starboard truss segments (S3/S4) which include a third set of solar arrays. In addition, the astronauts will retract the P6-2B wing, installed 6 years ago in a temporary location, to provide clearance for the rotation of the new Solar Alpha Rotary Joint (SARJ) and the deployed S4 solar arrays.

ATK designed and fabricated the truss structures which can both deploy the powerful 32-kilowatt solar arrays and retract them when required. ATK’s Folding Articulated Square Truss (FAST) Mast technology allows for a compact stowage length less than eight feet when fully retracted and more than 115 feet long when fully deployed. The FAST Mast canister is designed to fully retract and deploy the solar arrays 35 times during its expected 15-year on-orbit life. ATK’s FAST Mast successfully retracted the P6-4B ISS solar array wing during the STS-116 mission.

ATK’s patented structural bearing technology, consisting of a pair of gear driven 10.5 ft-diameter race rings connected by 12 evenly spaced trundles, will enable the SARJ, built by Lockheed Martin, to spin and allow for continuous rotation of the outboard truss structure to maintain optimum positioning of the solar arrays to the Sun; maximizing the solar power provided to the ISS. ATK designed the components to withstand temperature gradients approaching 100 degrees Fahrenheit.

STS-117 is the 118th shuttle flight and the 21st U.S. flight to the International Space Station. ATK solid rocket motors have flown on each Space Shuttle mission since the inception of the program in 1981, and today are the only human-rated solid rocket motors produced in the U.S.

ATK is a $3.9 billion advanced weapon and space systems company employing approximately 16,500 people in 21 states. 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: 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.