For Immediate Release For More Information Contact:
Barron Beneski (703) 406-5528
Public and Investor Relations
beneski.barron@orbital.com

ORBITAL'S CYGNUS CARGO MODULE ARRIVES AT NASA'S
WALLOPS FLIGHT FACILITY

-- Pressurized Cargo Module Built by Thales Alenia Space to be Flown on COTS Demonstration Mission in Early 2012 --

(Dulles, VA 25 August 2011) - Orbital Sciences Corporation (NYSE: ORB), one of the world's leading space technology companies, today announced that the first pressurized cargo module (PCM) for its Cygnus(TM) cargo logistics spacecraft has arrived at NASA's Wallops Flight Facility in eastern Virginia. Following a transatlantic flight from its manufacturing location in Italy, the PCM was unloaded from the Antonov An-26 transport aircraft in its specialized shipping container and was brought to NASA's H-100 payload processing facility where it will be uncrated later this week and prepared for integration with the spacecraft service module. Together, the PCM and the service module will form the first operational Cygnus that will be launched to the International Space Station (ISS) to carry out a demonstration mission under the Commercial Orbital Transportation Services (COTS) joint NASA and Orbital research and development program.

"The arrival of the first pressurized cargo module at Wallops is an important milestone for the Cygnus program, signifying that we are making great progress toward carrying out the COTS demonstration mission early next year," said Mr. Frank DeMauro, Orbital's Cygnus Program Manager. "With the first fully-assembled service module currently in testing at our Dulles, Virginia satellite design and production facilities, it won't be too long before both of the major elements are united at Wallops for final system integration, followed by integration with the Taurus II rocket that will launch Cygnus to the International Space Station."

The PCM was manufactured and tested by Thales Alenia Space (TAS) in Italy. Orbital selected TAS because of its unrivaled experience in designing and building pressurized space modules for the ISS. TAS is already well along in manufacturing and testing the next three PCM units for the Cygnus program, ensuring on-schedule deliveries of a critical element of the spacecraft. For the COTS demonstration and the first two operational Commercial Resupply Services (CRS) missions, the PCM is designed to carry approximately 2,000 kg of cargo. For later missions, an enhanced PCM will carry about 2,700 kg of cargo.

About Cygnus

The Cygnus advanced maneuvering spacecraft is being developed by Orbital to demonstrate cargo delivery services under the COTS agreement and to carry out ISS resupply flights under the $1.9 billion CRS contract, which encompasses eight missions between 2012 and 2015 carrying approximately 20,000 kg of cargo to the ISS.

The Cygnus system is a low-risk design incorporating elements drawn from Orbital and its partners' existing, flight-proven space systems technologies. Cygnus consists of an advanced service module and a PCM. The service module incorporates avionics, power and propulsion systems from Orbital's flight-proven LEOStar(TM) and GEOStar(TM) satellite product lines. Based on NASA's requirements, it will deliver crew supplies, scientific experiments and equipment, spares parts and other essential cargo to the ISS.

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:

High-resolution images of the Cygnus cargo logistics spacecraft can be found at:
http://www.orbital.com/NewsInfo/ImagesMultimedia/Images/ExplorationSystems

High-definition video animation of the Taurus II and Cygnus launch sequence to the ISS can be found at: http://www.orbital.com/NewsInfo/ImagesMultimedia/Video/

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