Orbital Sciences Corporation (NYSE: ORB), one of the world’s leading space technology companies, announced today that the HYLAS 2 satellite, built by the company for Avanti Communications Group PLC, was successfully launched into orbit aboard an Ariane 5 rocket from Kourou, French Guiana. The mission began on Thursday, August 2, 2012, with the lift-off of the Ariane 5 space launch vehicle at 4:54 p.m. (EDT). The satellite successfully separated from the rocket’s final stage approximately 34 minutes after liftoff.

Mr. Christopher Richmond, Orbital’s Senior Vice President of Communications Satellites, said, “The HYLAS 2 mission is going very well so far following another successful launch by Arianespace. Over the next several weeks, we will work with the engineering team from Avanti to conduct in-orbit testing to verify the spacecraft’s systems before it enters commercial service.”

“From design to early in-orbit activation and verification, execution of the HYLAS 2 satellite project has proceeded smoothly. We have worked closely with Avanti every step of the way, following our model of superior customer involvement throughout the program to ensure our customer’s needs are fully met,” added Richmond. “We are pleased to be a part of Avanti’s team, bringing exciting new applications and services to these fast-growing markets.” About HYLAS 2 The state-of-the-art smaller-size satellite is based on Orbital’s proven GEOStar-2 platform. It carries 24 active Ka-band user beams and six gateway beams and will produce approximately 5.0 kilowatts of payload electrical power. The Ka-band spot beams on the HYLAS 2 will provide two-way communications services to facilitate high-speed delivery of data to end-user applications such as corporate networking, broadband Internet access, business continuity services and video distribution. The spacecraft will be equipped with a steerable spot beam, also operating at Ka-band, which can provide coverage anywhere on Earth that is visible to the satellite. Orbital designed, built and tested the HYLAS 2 spacecraft at the company’s satellite manufacturing facility in Dulles, Virginia.

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

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Note to Editors: High resolution images of the HYLAS 2 satellite are available on Orbital’s web site at: http://www.orbital.com/NewsInfo/ImagesMultimedia/Images/SatelliteSpaceSystems/index.shtml