-- Culbertson to Become Senior Vice President of Advanced Programs
                           in Dulles, VA --

     -- 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 two experienced executives to fill new roles in its Advanced Programs and Launch Systems Groups' management teams, the company announced today. Mr. Frank L. Culbertson, Jr. has joined the company as Senior Vice President and Deputy General Manager of the Advanced Programs Group, based in Dulles, VA. Mr. Culbertson will be responsible for Orbital's human spaceflight programs, including commercial transportation services to the International Space Station (ISS) and the Orion Launch Abort System.

In addition to Mr. Culbertson's appointment, Orbital has also 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.

About Frank L. Culbertson

Prior to joining Orbital, Mr. Culbertson was a Senior Vice President at Science Applications International Corporation (SAIC), initially as Program Manager of the Safety, Reliability and Quality Assurance contract at the National Aeronautics and Space Administration (NASA) Johnson Space Center in Houston, Texas, before progressing to business unit general management and, most recently, Director of SAIC's Global Climate Change Programs. Before joining SAIC, Mr. Culbertson had a distinguished career as both an astronaut for NASA and as a Naval Aviator.

Mr. Culbertson was originally selected as a NASA astronaut candidate in 1984. For the next 18 years, he served in a variety of critical spaceflight and management roles for NASA's Space Shuttle and Space Station programs, including three launches aboard the Space Shuttle and command of the International Space Station. These flights included piloting STS-38 Atlantis in 1990, commanding STS-51 Discovery in 1993, and launching on STS-105 Endeavour to the ISS in 2001, plus returning aboard STS-108 Discovery after four months on the ISS. During Expedition 3 to the ISS, which began in August 2001 and returned to Earth in December 2001, Mr. Culbertson and his two Russian crewmates lived and worked in space for 129 days. In total, he has logged over 144 days in space and over five hours of extra-vehicular activity (space walk) experience.

While at NASA, Mr. Culbertson also served as Program Manager of the Shuttle-Mir Program for three years and Deputy Program Manager for Operations for the ISS program.

Mr. Culbertson is a graduate of the U.S. Naval Academy at Annapolis, MD. His career in the U.S. Navy included several deployments aboard aircraft carriers and tours as an instructor pilot and automatic carrier landing system test pilot. He has logged almost 7,000 hours flying time in 50 different types of aircraft and has made more than 350 carrier landings. He retired from active duty as a U.S. Navy Captain in 1997.

About Mark A. Pieczynski

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