DULLES, Va.May 24, 2004--Orbital Sciences Corporation (NYSE:ORB) announced today that its Chairman and Chief Executive Officer David Thompson and Vice Chairman and Chief Financial Officer Garrett Pierce will make a presentation to investors and analysts during the SunTrust Robinson Humphrey 33rd Annual Institutional Conference to be held in Atlanta, Georgia at the Ritz-Carlton Buckhead. Orbital's presentation is scheduled to take place at 1:20 p.m. (EDT) on Wednesday, May 26.

The sponsors of SunTrust Robinson Humphrey 33rd Annual Institutional Conference will be presenting the audio portion of the conference as a live webcast, which can be accessed at: http://www.wsw.com/webcast/strh9/orb/. To access the webcast, listeners are encouraged to register in advance and to select their preferred Internet media player program prior to the start of the presentation. In addition, Orbital will make available the PowerPoint presentation slides that Mr. Thompson and Mr. Pierce will present to the live audience on the company's web site at: http://www.orbital.com/Investor/.

Orbital will maintain a link to the audio replay of the conference and will keep the presentation slides available for seven days following the conference on the company's web site under the "For Investors" section.

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.

    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703-406-5528

    SOURCE: Orbital Sciences Corporation