Aerojet, a GenCorp (NYSE: GY) company, announced that its AJ26 engine was hot-fire tested today at NASA’s Stennis Space Center in Mississippi. In support of the Taurus(R) II launch vehicle program, Orbital Sciences Corporation (Orbital), Aerojet and NASA conducted this first of three hot-fire engine tests to be performed throughout the next several weeks.

Aerojet’s AJ26 engine is an oxidizer-rich, staged-combustion LO2/Kerosene engine that achieves very high performance in a lightweight compact package. Based on the NK-33 engine originally designed and produced in Russia for the Russian N1 lunar launch vehicle, the liquid-fuel AJ26 will provide boost for the first stage of the Taurus II launch vehicle. The engine tested today is the first of four engines to be tested at Stennis throughout the next several months. This testing is being conducted to support the Taurus II Initial Launch Capability (ILC) in the third quarter of 2011.

Aerojet originally purchased approximately 40 NK-33 engines in the mid-1990s and, under contract with Orbital Sciences Corporation, the company has modified the engines specifically for Orbital’s Taurus II medium-class launch vehicle. Throughout the years, more than 200 NK-33 engines were built and 575 engine tests conducted, totaling more than 100,000 seconds of test time. Aerojet has been developing design modifications to the NK-33 since that time to ensure that the AJ26 is suitable for commercial launchers.

“Aerojet is looking forward to more successes like this throughout the Taurus II program,” said Executive Director, Pete Cova. “This is a great opportunity to take the NK-33 engines and convert them into another application for medium-class launch vehicles.”

Orbital, Aerojet and NASA Stennis personnel completed facility upgrades to accommodate today’s AJ26 testing. In addition to the AJ26 certification testing, each AJ26 engine to be used in the Taurus II program will come through the Stennis facility for pre-launch acceptance testing prior to being integrated with the rocket at NASA’s E-1 test stand.

Aerojet is a world-recognized aerospace and defense leader principally serving the missile and space propulsion, defense and armaments markets. GenCorp is a leading technology-based manufacturer of aerospace and defense products and systems with a real estate segment that includes activities related to the entitlement, sale, and leasing of the company’s excess real estate assets. Additional information about Aerojet and GenCorp can be obtained by visiting the companies’ Web sites at http://www.Aerojet.com and http://www.GenCorp.com.

About Taurus II

The Taurus II medium-class space launch vehicle is being developed to boost payloads into a variety of low-Earth and geosynchronous transfer orbits and to Earth escape trajectories. Taurus II incorporates proven technologies from Orbital’s Pegasus(R), Taurus(R) and Minotaur rockets, and is supported by a “best-in-class” network of suppliers from the U.S. and around the world.

The Taurus II rocket will also be available to civil government and U.S. military customers for dedicated launch services for medium-class scientific and national security satellites. Taurus II will also be capable of supporting mid-inclination and polar orbiting spacecraft weighing 10,000 lbs. and 5,500 lbs., respectively.