Operational Control of Satellite Turned Over to Avanti Communications

(Dulles, VA 10 September 2012) — Orbital Sciences Corporation (NYSE: ORB), one of the world’s leading space technology companies, announced today that the HYLAS 2 high-throughput broadband satellite has completed its in-orbit testing and operational control has been turned over to the customer, Avanti Communications Group PLC. HYLAS 2 was launched aboard an Ariane 5 rocket from Kourou, French Guiana in on August 3, 2012. A team of Avanti and Orbital engineers have since conducted several weeks of orbit raising and testing operations to prepare the spacecraft for commercial service.

“This is the most complex satellite we have ever built. We couldn’t be more pleased with how the post-launch operations of HYLAS 2 have proceeded,” said Mr. Christopher Richmond, Orbital’s Senior Vice President of its Space Systems Group. “The satellite is functioning as it should, and we have turned over full operational control to Avanti.”

Post-launch activities included the successful completion of a comprehensive set of tests to verify the performance of the satellites various subsystems such as propulsion, data handling, electrical, attitude control, thermal, flight software and telemetry. The satellite’s three reflectors were successfully deployed, including two east-and-west reflectors, and the nadir reflector, as well as the two solar arrays that provide the satellite’s electrical power.

Orbital designed, built and tested the HYLAS 2 satellite at Orbital’s satellite manufacturing and test facility in Dulles, VA. It carries 24 active Ka-band user beams and six gateway beams and will produce approximately 5.0 kilowatts of payload electrical power. The HYLAS 2 is also equipped with a steerable spot beam, also operating at Ka-band, which can provide coverage anywhere on Earth that is visible to the satellite. HYLAS 2 will provide data and video services to Northern and Southern Africa, Eastern Europe and the Middle East and across the Caucuses.

HYLAS 2 is the latest of Orbital’s highly successful GEOStar(TM) satellite platform, which is able to accommodate all types of commercial communications payloads. The GEOStar design is optimized for satellite missions requiring up to 7.5 kilowatts of payload power. In most instances, the affordable GEOStar satellite can be built and delivered in about 24 months.

About Avanti Communications Group PLC

Avanti sells satellite data communications services to telecommunications companies which use them to supply residential, enterprise and institutional users. Avanti’s first satellite, called HYLAS 1, launched on November 26, 2010, was the first Ka-band satellite launched in Europe. Avanti’s second satellite, HYLAS 2, will extend Avanti’s coverage to Africa and the Middle East. Avanti’s third satellite, HYLAS 3, to be launched in partnership with ESA in 2015, will provide further capacity in the EMEA region. Some 80% of Avanti’s fleet capacity will address the emerging telecommunications markets of Africa and the Middle East. For more information about Avanti, media are asked to contact:

College Hill, London: +44 (0)207 457 2020 and ask for:

* Duncan MacKenzie-Reid, duncan.mackenzie-reid@collegehill.com
* Jeremy Durrant, Jeremy.durrant@collegehill.com
* Lottie Whyte, lottie.whyte@collegehill.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