DULLES, Va.June 2, 2008--Orbital Sciences Corporation (NYSE:ORB) announced today that its Vice Chairman and CFO Garrett E. Pierce will make a presentation to investors and analysts during Sidoti & Company's Fifth Annual Emerging Growth Institutional Investor Forum to be held in Boston, Massachusetts. Orbital's presentation is scheduled to take place at 3:25 p.m. (EDT) on Tuesday, June 3.

Orbital will make available the presentation slides that Mr. Pierce will present to the live audience on the company's web site at: http://www.orbital.com/Investor/. The slides will be posted prior to the beginning of the live presentation.

About Orbital

Orbital develops and manufactures small 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 offers space-related technical services to government agencies and develops and builds software-based transportation management systems for public transit agencies and private vehicle fleet operators.

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

    SOURCE: Orbital Sciences Corporation