DULLES, Va.Dec. 10, 2008--Orbital Sciences Corporation (NYSE:ORB) announced today that it will hold the official ribbon cutting ceremony for its new Building #7 at the company's Dulles, VA campus on Monday, December 15, 2008. Official remarks will begin at 12:00 noon. Media should plan to arrive no later than 11:45 a.m. Further details of the event are below.

Background:

Orbital has embarked on a major expansion to its headquarters and satellite and space systems manufacturing facilities in Dulles, Virginia. Orbital currently occupies over 500,000 square feet and employs approximately 1,700 people at its Dulles campus in Loudoun County. To accommodate its growth in business activity and employees, Orbital has completed the first of up to four new buildings that will add another 220,000 square feet of office and engineering space capable of housing another 600 employees. 


Where:          Orbital's Dulles, Virginia Campus - Building #7

                45370 Steeplechase Drive

                Dulles, Virginia 20166

Date:           December 15, 2008

Time:           Official remarks begin at 12:00 noon

Speakers/Ribbon Cutting Participants:

-- Mr. David W. Thompson - Orbital's Chairman and Chief Executive Officer

-- Congressman Frank Wolf (10th Virginia District)

-- Virginia State Senator Mark Herring (33rd Virginia Senate District)

-- Loudoun County Supervisor Andrea McGimsey (Potomac District)

Agenda:         12:00 noon Official remarks

                12:30 p.m. Ribbon cutting ceremony, photo opportunities and
                interviews with ceremony participants

                12:30 p.m. Guest reception

                1:30 p.m. End of event

Media Parking:  Building #7 parking lot. Follow directional signs from Route 28.

About Orbital

Orbital is one of the largest employers in Loudoun County, with approximately 1,700 space industry professionals employed at the company's Dulles campus. Orbital is expected to generate over $1.1 billion in annual revenues in 2008 and employs approximately 3,700 people nationwide.

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 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 government agencies and laboratories. 


    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703-406-5528
             Public and Investor Relations
             beneski.barron@orbital.com

    Source: Orbital Sciences Corporation