-- Orbital to Provide its STAR(TM) Spacecraft Platform and Perform Integration Work at its Dulles, VA Satellite Manufacturing Facility --

   -- Thales Alenia Space to Serve as Program's Prime Contractor and
                          Payload Supplier --

DULLES, Va.May 14, 2008--Orbital Sciences Corporation (NYSE:ORB) today announced that it has signed a contract with Thales Alenia Space of France to supply its STAR satellite platform and carry out final spacecraft, payload and system integration and testing for the Koreasat 6 commercial communications satellite to be built for KT Corporation of the Republic of Korea. The spacecraft's engineering, manufacturing, integration and test activities will take place at Orbital's satellite manufacturing facility located in Dulles, VA. Thales Alenia Space will act as prime contractor for the project, provide the communications payload and deliver the Koreasat 6 satellite to KT.

At its final orbital slot at 116 degrees East Longitude, the Koreasat 6 satellite will carry 30 active Ku-Band channels that provide Direct Broadcast Services (DBS) and Fixed Satellite Services (FSS) to the people of Korea. The STAR-2 platform will support 3.4 kilowatts of payload power and will have a 15-year on-orbit mission life. Koreasat 6 is scheduled to be delivered and launched in mid- to late-2010.

The Koreasat 6 spacecraft is the second to be purchased in 2008 that uses Orbital's STAR platform. Earlier this year, the company announced a follow-on order from SES Americom for its fourth STAR satellite purchased in the last two years. With the Koreasat 6 contract award, Orbital currently has 10 commercial communications satellites in various stages of design and production for launches between 2008 and 2010.

"Orbital is proud and excited to be part of the Koreasat 6 program in partnership with Thales Alenia Space," said Mr. Christopher Richmond, Senior Vice President of Orbital Global Communications. "Our flight-proven STAR-2 bus is the perfect fit for a Thales-built payload that will provide valuable DBS and FSS services to KT, the top telecommunications company in Korea. We look forward to the start of a successful program with our partners in Korea and France."

About Orbital

Orbital develops and manufactures small 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 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 offers space-related technical services to government agencies and develops and builds software-based transportation management systems for public transit agencies and private vehicle fleet operators.

    CONTACT: Orbital Sciences Corporation
             Barron Beneski (703) 406-5528
             Public and Investor Relations

    SOURCE: Orbital Sciences Corporation