ATK (Alliant Techsystems) announced today that it successfully flight-tested a first stage
rocket motor aboard an Orbital Sciences Corporation interceptor
boost vehicle being developed for the U.S. Ground-based Missile Defense (GMD)
system. This was the first such launch from a Vandenberg Air Force Base,
Calif. silo. The GMD vehicle was tested in a ground-launch configuration
earlier this year. Both launches contained simulated payloads.

ATK Thiokol Propulsion was selected last year to be the solid propulsion
supplier on the Orbital team that is developing the boost vehicle for Boeing,
the prime contractor on the GMD program.

The three-stage boost vehicle uses slightly modified Orion motors, which
are manufactured by ATK Thiokol Propulsion at its rocket motor facility in
Magna, Utah and flown on the Orbital Taurus® and Pegasus® launch vehicles.

The first-stage Orion 50SXLG motor is a stretched version of the standard
Taurus motor, and is similar to the Pegasus XL first-stage motor, but with
more solid propellant for increased performance. It includes a more robust
nozzle with a shortened exit cone for ground launch capability, and a new
Orbital thermal blanket/aft skirt and thrust vector actuation system. The
second and third stages use flight-proven Pegasus XL motors.

ATK is a $2.2 billion aerospace and defense company with strong positions
in propulsion, composite structures, munitions, precision capabilities, and
civil and sporting ammunition. The company, which is headquartered in Edina,
Minn., employs approximately 12,000 people and has three business groups:
Aerospace, Precision Systems, and Ammunition and Related Products. ATK news
and information can be found on the Internet at .

Certain information discussed in this press release may constitute
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: unforeseen delays in NASA’s Space Shuttle program, changes in
governmental spending and budgetary policies, economic conditions, equity
market returns, the company’s competitive environment, the timing of awards
and contracts, the outcome of contingencies, including litigation and
environmental remediation, program performance, and sales projections. 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 annual reports on Form 10-K.