(Dulles, VA 9 September 2004) – Orbital Sciences Corporation (NYSE: ORB)
announced today that Mr. G. David Low has been named Vice President of its
Technical Services Division (TSD), headquartered in Greenbelt, MD. Mr. Low
will succeed Mr. Richard Hicks, who is remaining with TSD on a part-time
basis as an advisor on existing contracts and new business opportunities.
Mr. Hicks has held various positions in the aerospace industry over the past
43 years and is entering into partial retirement. Mr. Low assumed his new
post on September 7.

“It is with great confidence in David’s abilities that we announce his
appointment as the new head of our Technical Services Division,” said Mr.
Jack Danko, Orbital’s Executive Vice President and General Manager of its
Space Systems Group. “His credentials as a senior Orbital manager and
extensive knowledge of and background with NASA, TSD’s principal customer,
represent a perfect fit for the TSD business.”

Mr. Danko also added, “I am also pleased that Dick Hicks has agreed to
remain active in the TSD business. Orbital will continue to benefit from the
insight and wisdom he gained during his many years in the industry.”

Mr. Low has served with Orbital for the past eight years, joining the
company’s Launch Systems Group in 1996 as Vice President of Safety and
Mission Assurance, spearheading the Group’s ISO qualification effort. In
addition to holding several other senior positions in the company, Mr. Low
most recently served as Vice President and Deputy General Manager of
Orbital’s Advanced Programs Group. In this role, he helped lead the
company’s participation in NASA’s efforts to develop new human space
exploration systems.

Prior to joining Orbital, Mr. Low was a NASA astronaut from 1984 until 1996.
During this time he flew on three Space Shuttle missions as a mission
specialist, flight engineer and payload commander. During his more than 700
hours in space, Mr. Low helped to deploy two communications satellites and
retrieve two scientific satellites using the Shuttle’s robotic arm. He also
conducted a six-hour spacewalk and participated in numerous scientific and
medical experiments. Mr. Low began his career with NASA in 1980 as a
spacecraft systems engineer for the Jet Propulsion Laboratory.

Mr. Low holds a B.S. in Physics-Engineering from Washington and Lee
University, a B.S. in Mechanical Engineering from Cornell University, an
M.S. in Aeronautics and Astronautics from Stanford University and an MBA
from Johns Hopkins University. He has also completed the Advanced Management
Program at Harvard Business School.

Mr. Low is a recipient of the NASA Outstanding Leadership Medal, the NASA
Exceptional Service Medal, three NASA Space Flight Medals and an honorary
Doctor of Engineering Degree from Rensselaer Polytechnic Institute. He is an
Associate Fellow of the AIAA.

Mr. Low resides in Potomac Falls, Virginia with his wife JoAnn and their
three children.

About Orbital

Orbital develops and manufactures small space and rocket systems for
commercial, military and civil government customers. The company’s primary
products are satellites and launch vehicles, including low-orbit,
geosynchronous and planetary spacecraft for communications, remote sensing,
scientific and defense 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 offers space-related technical
services to government agencies and develops and builds satellite-based
transportation management systems for public transit agencies and private
vehicle fleet operators.

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Note to editors:

· A high-resolution photo of Mr. Low is available on Orbital’s web site at: http://www.orbital.com/images/high/David_Low.jpg