SACRAMENTO, Calif., Feb. 22, 2013 – Aerojet, a GenCorp (NYSE: GY) company, announced that its dual AJ26 main engine system successfully powered today’s Antares(TM) Stage 1 Hot Fire test conducted by Orbital Sciences Corporation (NYSE: ORB) at the Mid-Atlantic Regional Spaceport located at NASA’s Wallops Flight Facility on the eastern shore of Virginia.

The 29-second test enabled engineers to validate flight configuration checkout of the Antares main engine system and first stage booster. During this “strap down” test, the AJ26 engines produced approximately 680,000 lbs of sea-level thrust.

“Today’s successful stage test positions us one step closer to supporting Orbital’s historic flight test,” said Aerojet Vice President of Space & Launch Systems, Julie Van Kleeck. “We’re proud to deliver for the Antares team and we’re looking forward to continuing the countdown toward the inaugural mission.”

The AJ26 is a commercial derivative of the NK-33 engine that was first developed for the Russian N-1 rocket. The NK-33, oxidizer-rich, staged-combustion LO2/Kerosene engine is among the highest thrust-to-weight ratio of any Earth-launched rocket engine.

“Aerojet purchased the NK-33 engines from JSC Kuznetsov in the mid-1990s and has been developing design modifications to ensure that the AJ26 is suitable for U.S. commercial launch vehicles,” said Aerojet Executive Director of Space & Launch Systems, Pete Cova. “As teammates, JSC Kuznetsov brings tremendous technical support to our efforts and we are looking forward to supporting Orbital in its Cargo Resupply Contract with NASA.”

Aerojet is a world-recognized aerospace and defense leader providing propulsion and energetics to the space, missile defense, strategic, tactical missile and armaments areas in support of domestic and international 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’ websites at http://www.Aerojet.com and http://www.GenCorp.com.