-- Company Consolidates its Chandler Operations with Ribbon Cutting Ceremony for
New 83,000 sq. ft. Building --

-- Expansion Increases Orbital’s Total Phoenix-Area Presence to Over 600,000 Square Feet --

DULLES, Va.Sep. 17, 2009-- Orbital Sciences Corporation (NYSE: ORB), one of the world’s leading space technology companies, today conducted a ribbon-cutting ceremony to formally mark the opening of a new 83,000 square foot building adjacent to the company’s current facilities on South Price Road in the Ocotillo area of Chandler, Arizona. The building will house approximately 300 employees in the company’s launch vehicle design, engineering, manufacturing, and program management operations.

The opening of the new building, which was constructed under a “build-to-suit” agreement with Gilbane Development Company, follows the company’s 11-year renewal of the lease on its current facility with W.P. Carey & Co., ensuring that orbital will remain an anchor corporate tenant in Chandler for at least the next decade. With the addition of the new building and expansion of its Tempe warehouse facilities, the company occupies over 600,000 square feet of engineering, manufacturing and testing facilities in the Greater Phoenix area.

“For over 20 years we have enjoyed a very business-friendly environment in Chandler,” said Mr. David W. Thompson, Orbital’s Chairman and Chief Executive Officer. “We are most appreciative of the City’s responsiveness to our expansion plan. In turn, we are very pleased to continue to grow in the area, adding to the dynamic local business environment and generating significant economic benefits for the community.”

Orbital’s long-term plans for the Chandler campus, subject to future business considerations, include the construction of two additional buildings totaling up to 150,000 square feet. Together with the company’s current on-site facilities, the new development would create a 48-acre campus with approximately 650,000 square feet of engineering, industrial and administrative space that will be capable of accommodating about 2,200 employees. Orbital currently employs approximately 1,450 full- and part-time employees at its Chandler operations.

Orbital’s multi-year expansion in Chandler has been fueled by the continued strong demand for the company’s launch vehicle products that are used primarily by the U.S. government to deploy and test critical missile defense systems, and to launch scientific and national security satellites. Orbital is also developing a new space launch vehicle, the Taurus II rocket, which will carry out cargo transportation missions to the International Space Station and launch larger satellites into orbit.

In addition to the company’s expansion of its Arizona facilities, in late 2008 Orbital completed the first of up to four new buildings at its Dulles, Virginia headquarters and satellite and space systems manufacturing facilities. Orbital currently occupies over 565,000 sq. ft. at its 77-acre Northern Virginia campus accommodating approximately 1,600 full- and part-time employees.

Orbital has also opened two new offices to support its expanding involvement in human spaceflight systems for NASA and national security space programs for the U.S. military. To better serve existing customers and pursue new business opportunities in these areas, the company established an engineering and technology center in Huntington Beach, California and opened an office in Houston, Texas. Nationwide, Orbital occupies over 1.35 million square feet of office, laboratory, manufacturing, test and warehouse space and employs approximately 3,600 people.

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 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.

More information about Orbital can be found at http://www.orbital.com

Source: Orbital Sciences Corporation

Orbital Sciences Corporation
Public and Investor Relations
Barron Beneski, 703-406-5528