Russian Tests of Heritage NK-33 Rocket Engine Confirm Performance and Durability

Engine Completes Two Times Normal Firing Duration of a Taurus II Launch Profile

SACRAMENTO, Calif., March 15, 2010 – Aerojet, a GenCorp (NYSE: GY) company, and Orbital Sciences Corporation (NYSE: ORB), along with Aerojet’s Russian partner, SNTK, announced today that a series of NK-33 rocket engine tests conducted in Samara, Russia were successfully completed in support of the development of Orbital’s Taurus(R) II space launch vehicle.

The purpose of the extended-time testing of the NK-33 engine, on which the AJ26 first-stage engine for the Taurus II rocket is based, was to demonstrate a ‘hot-fire’ duration equal to two times a normal Taurus II acceptance testing and launch profile duty cycle. Over the last two weeks, three tests were conducted by SNTK with a cumulative duration of more than 600 seconds. These tests verified the significant technical margins on engine performance and durability required by Orbital’s Taurus II development program.

GenCorp President and CEO and Aerojet President, Scott Seymour, said, “Completing the margin testing is a significant milestone in Aerojet’s contract with Orbital. This success demonstrates the engine’s robust design and its ability to operate at the power levels and duration times compatible with the Taurus II flight profile with additional performance margin.”

“The success of the NK-33 engine tests in Russia is an important step forward in the development of the Taurus II rocket,” said Ron Grabe, Orbital’s Executive Vice President and General Manager of its Launch Systems Group. “With the performance of the heritage engine now confirmed and well understood, we can move forward with confidence to configuration verification and acceptance testing of AJ26 engines at NASA’s Stennis Space Center in Mississippi beginning in April.”

Aerojet is the provider of the AJ26/NK-33 rocket engine for the first stage of the Taurus II launcher. The basic NK-33 engine was originally designed and produced in Russia for the Russian N1 lunar launch vehicle. Aerojet subsequently purchased approximately 40 of the basic NK-33 engines in the mid-1990s and, under contract with Orbital, the company is currently modifying the engines specifically for the Taurus II launch vehicle.

Aerojet and Orbital are scheduled to begin ground testing of the AJ26 engine at NASA’s Stennis Space Center in Mississippi in less than two months. The U.S.-based testing will validate the Taurus II specific engine configuration and continue to build on the extensive engine database that includes more than 17 years of development testing, encompassing approximately 1,500 engine-level tests totaling 194,000 seconds of firing duration. After the design verification tests are completed at Stennis, regular production acceptance testing will be initiated, paving the way to the first flights of the Taurus II rocket in 2011.

About the AJ26 Rocket Engine

The AJ26 is a commercial derivative of the NK-33 engine that was first developed for the Russian rocket that would have taken cosmonauts to the moon. As the world’s first oxidizer-rich, staged-combustion, oxygen/kerosene rocket engine, it achieves very high performance in a lightweight, compact package. Aerojet has been developing design modifications to make the engine suitable for commercial launchers since the mid-1990s.

About the Taurus II Launch Vehicle

Orbital is developing the Taurus II medium-class space launch vehicle to boost payloads into a variety of low Earth and geosynchronous transfer orbits and to Earth escape trajectories. Taurus II incorporates proven technologies from the company’s Pegasus(R), Taurus 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 program currently has a backlog of nine launches, beginning with the demonstration flight in 2011 for the Commercial Orbital Transportation Services (COTS) project, a joint research and development effort with NASA to develop a system capable of safely and reliably supplying the International Space Station (ISS) with essential cargo. Orbital is also under contract with NASA for the Commercial Resupply Services (CRS) program with an eight-mission, $1.9 billion agreement to deliver cargo to the ISS from 2011 through 2015.

In addition to its work with NASA on the COTS and CRS programs, Orbital is also offering the Taurus II rocket to U.S. civil government and military customers for dedicated launch services for medium-class scientific and national security satellites. From its Wallops Island, Virginia launch site, Taurus II will be capable of supporting mid-inclination and polar orbiting spacecraft weighing approximately 10,500 lbs. and 5,500 lbs., respectively.

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 Orbital

Orbital develops and manufactures small- and medium-class rockets and space systems for commercial, military and civil government customers. The company’s primary products are satellites and launch vehicles, including low-Earth orbit, geosynchronous-Earth orbit and planetary exploration spacecraft for communications, remote sensing, scientific and defense missions; human-rated space systems for Earth-orbit, lunar and other missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense systems that are used as interceptor and target vehicles. Orbital also provides satellite subsystems and space-related technical services to U.S. Government agencies and laboratories. More information about Orbital can be found at http://www.orbital.com
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Notes to Editors:

Downloadable images of Aerojet’s AJ26 engine can be found at:
http://www.aerojet.com/capabilities/spacelift.php

Downloadable images of Orbital’s Taurus II rocket can be found at:
http://www.orbital.com/NewsInfo/ImagesMultimedia/Images/ExplorationSystems/index.shtml