DULLES, Va.Nov. 26, 2007--Orbital Sciences Corporation (NYSE:ORB) announced today that its Chairman and CEO David W. Thompson will make a presentation to investors and analysts during the 2007 Annual Credit Suisse/Aviation Week Aerospace and Defense Conference to be held in New York City on November 29. Orbital's presentation is scheduled to begin at 11:30 a.m. (EST).

On the day of the conference, Orbital will provide a link to a live audio webcast of the presentation and will post the informational slides that Mr. Thompson will present to the audience on the company's web site at: http://www.orbital.com/Investor/. The slides will be posted prior to the beginning of the Mr. Thompson's 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-orbit, geosynchronous-orbit 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
             Public and Investor Relations

    SOURCE: Orbital Sciences Corporation