Former White House Director of Space Policy Joins Companys Strategic Planning Team to Address Future Opportunities in Government Space Programs

(Dulles, VA 29 November 2010) – Orbital Sciences Corporation (NYSE: ORB) announced today that former White House Space Policy Director Peter J. Marquez has joined the company as Vice President of Strategy and Planning. In his new role, Mr. Marquez will be responsible for helping to develop the company’s strategic approach to opportunities in civil and military space programs that can be addressed with Orbital’s reliable and affordable small- and medium-class space systems. He will report to Senior Vice President Michael Hamel, Lt. Gen., U. S. Air Force (retired), who heads the company’s corporate strategy and development activities.

“Orbital is very pleased to welcome Peter to our senior management team. His recent background in formulating and implementing a comprehensive update to the nation’s space policy will bring the company extraordinary insight into how we can best serve the country’s space needs and interests in a difficult budget environment,” said Mr. Hamel. “The time is especially opportune for Peter to join Orbital, as the government is currently considering the future direction of space programs to allow civilian agencies and defense and intelligence customers to accomplish their critical missions. Orbital is well-positioned to support these government procurement initiatives and Peter’s knowledge will help us advance our strategic interests.”

For the past decade, Mr. Marquez has held senior positions with government and commercial organizations involved in U.S. space policy and programs. Just prior to joining Orbital, he served as the White House Director of Space Policy, a position he held since late 2007. Mr. Marquez transitioned to the White House from the Department of Defense, where he entered government service in 2002. He worked in the Office of the Under Secretary of Defense for Policy, first as a Space Policy Analyst, in which he helped formulate space policy and maintained oversight of the space control portfolio, eventually rising to Director of Special Programs, a role in which he oversaw all operational Defense Department Special Access Programs. Mr. Marquez came to the government from the private sector, where he began his career in 2000 with AT&T Government Solutions as an analyst for policy and programs for classified space and cyber capabilities.

Commenting on his new role with Orbital, Mr. Marquez said, “Orbital is uniquely positioned to continue its leadership in an environment of shifting government requirements. The company’s extensive history of producing highly reliable products based on the right combination of world- class engineering, lean business practices and agile system development will be critical to the U.S. government achieving its goals of fielding space capabilities that are more affordable, resilient and adaptable to the needs of many users. I am looking forward to helping the company play a leading role in the commercial, civil government and national security space sectors, both in the U.S. and abroad.”

Mr. Marquez earned a B.A. degree in Political Science and a M.A. degree in Space Policy and Science and Technology Policy, both from The George Washington University in Washington, DC. 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.