DULLES, Va.Oct. 2, 2003--

Air Force Exercises First Option Under the 10-Year, $475 Million Orbital/Suborbital Program

New Order Represents the Fourth Minotaur Rocket Currently Under Firm Contract

Orbital Sciences Corporation (NYSE:ORB) announced today that the U.S. Air Force has exercised an option order for a Minotaur space launch vehicle under the 10-year Orbital/Suborbital Program-2 (OSP-2) contract that was awarded to the company earlier this year. The Minotaur order is the first to be placed under the OSP-2 contract, which is valued at up to $475 million over 10 years on an indefinite delivery/indefinite quantity basis. The new order increases the launch manifest for the Minotaur program to four missions to be carried out over the next two years. This most recent Minotaur space launch vehicle ordered by the Air Force is scheduled to launch a classified payload in 2005. In addition, Orbital is currently under firm contract to carry out three other Minotaur missions, including N-FIRE and XSS-11, both of which are scheduled to be launched in 2004, and COSMIC, scheduled for launch in 2005.

"We are very pleased to have the opportunity to conduct cost-effective military space missions for the Department of Defense," said Mr. Ron Grabe, Orbital's Executive Vice President and General Manager of its Launch Systems Group. "The Minotaur program represents an efficient use of government assets and commercial technology to provide low-cost, operationally responsive and reliable launch services for U.S. government customers."

Orbital originally developed the four-stage Minotaur rocket under the Air Force's OSP-1 contract, which was awarded to the company in 1997. The Minotaur vehicle uses government-supplied Minuteman II rocket motors that serve as the vehicle's first and second stages. The rocket's third and fourth stages, as well as its guidance and control system, use technology from Orbital's highly reliable Pegasus XL commercial rocket program.

Orbital has carried out two previous Minotaur missions, both of which were fully successful. In January 2000, Minotaur made its successful debut with the launch of the JAWSAT spacecraft. Later in 2000, the second Minotaur rocket successfully launched the MightySat-II satellite into low-Earth orbit. Both missions were conducted from launch facilities at Vandenberg Air Force Base (VAFB), CA.

Over the past several years, Orbital has experienced rapid growth in its launch vehicle programs for military space and missile defense-related missions. The company's launch vehicle business is primarily centered at Orbital's engineering and production facility in Chandler, AZ, where the company employs approximately 800 people. Orbital also maintains launch vehicle assembly, integration and test facilities at VAFB, where the company employs nearly 100 people.

About Orbital

Orbital develops and manufactures small space systems for commercial, civil government and military customers. The company's primary products are satellites and launch vehicles, including low-orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters 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.

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

Note to Editors: High-resolution photos of the Minotaur space launch vehicle are available on Orbital's web site at: http://www.orbital.com/NewsInfo/Images/SpaceLaunch/index.html

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

    SOURCE: Orbital Sciences Corporation