Alliant Techsystems’ (NYSE: ATK) Reusable Solid Rocket Motors (RSRM) ignited at 6:03 p.m. EDT, launching the Space Shuttle Endeavour and its crew on their 16-day mission to the International Space Station (ISS). More than 100 RSRM flight sets have been launched to date, marking a two-decade track record of flawless performance.

“Today’s launch of the twin solid rocket motors is a continued demonstration of ATK’s commitment to safety and mission assurance,” said Blake Larson, ATK Space Systems president. “These motors prove time and time again how significant a role ATK plays in NASA’s space program.”

The 149-foot tall solid rocket boosters each produced more than 15 million horsepower, launching the shuttle to approximately 28 miles in altitude in just over two minutes. After their flight, the RSRMs were jettisoned from the orbiter and external tank by ATK’s 16 Booster Separation Motors (BSM). Each booster has eight BSMs: four on the forward skirt and four on the aft skirt. The separation motors propelled the RSRMs to a safe distance from the shuttle orbiter, enabling the spent boosters to parachute down through the Earth’s atmosphere where they splashed down into the ocean and were recovered for reuse. The solid rocket motors were produced at ATK’s facility in Promontory, Utah.

Along with the rocket motor technology, ATK supplied the titanium hydrazine propellant tanks for the space shuttle Auxiliary Power Unit (APU), manufactured at ATK’s Commerce, Calif., facility. Three APU tanks house the hydrazine fuel which generates power for the shuttle’s hydraulic system. These tanks have provided flawless performance during the shuttle’s three-decades of operations.

This is the 29th shuttle mission to the ISS, a mission that will expand the station’s scientific capabilities and bring its occupancy to an all-time high of 13 crew members. The astronauts will perform five spacewalks to conduct repairs, and to install the external experiment platform for the Japanese science laboratory, Kibo, which is being delivered by Endeavour.

Since the inaugural flight of the space shuttle, ATK and NASA have constantly improved their techniques and processes to increase the safety and mission reliability of the RSRMs. These motors have undergone countless subscale material characterization tests that tie together complex analyses with hard data. They have also undergone 27 full-scale ground tests, including a successful five-segment static test performed in October of 2003.

“The numerous upgrades and investment that ATK and NASA have put into the RSRM directly benefit the Ares program which will replace the Space Shuttle,” said Mike Kahn, ATK Space System executive vice president. “These motors showcase our commitment to quality and safety as we support the remaining shuttle missions and prepare for the launch of Ares I-X and Ares I.”

The remaining shuttle flights will be supported by ATK’s rocket motors while similar versions of the RSRM and BSMs motors are being tested and developed to be used on NASA’s newest crew launch vehicle, Ares I. The Ares vehicle will replace the shuttle and will continue to support missions to the ISS as well as take America back to the surface of the Moon and beyond. ATK is the prime contractor for the Ares I five-segment first stage.

ATK is a premier aerospace and defense company with more than 18,000 employees in 22 states, Puerto Rico and internationally, and revenues in excess of $4.7 billion. News and information can be found on the Internet at 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; assumptions related to the development of next-generation human-rated launch vehicles, 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.