DULLES, Va.Oct. 15, 2004--Orbital Sciences Corporation (NYSE:ORB) announced today that it will release its third quarter 2004 financial results prior to the opening of the market on Thursday, October 21, 2004. At 9:00 a.m. (EDT), Orbital will conduct a conference call with financial analysts and investors. The conference call will be hosted by the company's senior executives, including:

    --  Mr. David W. Thompson, Chairman and Chief Executive Officer

    --  Mr. Garrett E. Pierce, Vice Chairman and Chief Financial
        Officer

    --  Mr. James R. Thompson, Vice Chairman and Chief Operating
        Officer

To listen to the conference call, dial (888) 541-8767 and use the conference ID number 1590678. A replay of the conference call will be available approximately two hours after the end of the call and will remain active for five business days. To listen to the replay, dial (800) 642-1687.

To access the live webcast visit Orbital's web site at http://www.orbital.com/Investor. The company advises participants to register at least 20 minutes prior to the call to download and install any necessary audio software.

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.

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


    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703-406-5528
             beneski.barron@orbital.com

    SOURCE: Orbital Sciences Corporation