-- Pieczynski Appointed Vice President of Southern California
             Engineering Center in Huntington Beach, CA --

DULLES, Va.Aug. 27, 2008--Orbital Sciences Corporation (NYSE:ORB) has named Mr. Mark A. Pieczynski as Vice President of the company's new Southern California Engineering Center in Huntington Beach, CA. In his position, Mr. Pieczynski will oversee the technical support provided to Orbital's various launch vehicle and space systems programs from the company's newest facility, as well as being responsible for on-site staff management and development. In particular, Mr. Pieczynski will support the company's strategic goal of evolving the new Huntington Beach engineering facility to be a center of excellence for liquid rocket propulsion.

Since 1995, Mr. Pieczynski has held a series of senior-level positions on Delta launch vehicle programs for McDonnell Douglas, The Boeing Company and, most recently, United Launch Alliance (ULA) that included responsibility for engineering, manufacturing and launch site activities, as well as contractual and financial matters. From 1995 to 2002, he served as the Program Manager for the deployment of Iridium low-Earth orbit communications satellites aboard Delta II rockets. In 2002, he was promoted to Director of U.S. Air Force Delta II Programs, overseeing the launch of military spacecraft for the U.S. Department of Defense and its agencies such as the National Reconnaissance Office, Defense Advanced Research Projects Agency and Naval Research Laboratory.

For the past 15 months, Mr. Pieczynski served as the Delta Program Site Executive in Southern California, overseeing a workforce of over 900 ULA employees. He was responsible for coordinating the transition process for the ULA employees at the Huntington Beach location while all Delta rocket programs were being moved to ULA's new Denver, CO location. His areas of responsibility in that process included maintaining a program knowledge base to successfully transition the programs, serving as the primary interface between Boeing and ULA, and overseeing all employee-related transition activities for those employees who chose to relocate and those who chose not to transfer to the Denver location.

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.

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

    SOURCE: Orbital Sciences Corporation