DULLES, Va.Sept. 13, 2005--Orbital Sciences Corporation (NYSE:ORB) announced that its Transportation Management Systems division (Orbital TMS) has received system acceptance from the City of Phoenix Transit Department, a Valley Metro member, for the metro area's Vehicle Management System (VMS). The system will provide to Valley Metro, the organization comprised of the 11 Phoenix metro-area transit agencies, both in-vehicle hardware and control center software solutions for their mass-transit fleets.

Mr. Steve Brown, Deputy Public Transit Director for the City of Phoenix and Executive Sponsor of the VMS project, said, "The new Business Operating Procedures that were developed during this project and the fundamental change that we made to the way we do business allows us to proactively manage our regional transit system and provide significantly better service to our 55 million annual passengers. The automated next-stop announcements, both verbal and visual, allow us to greatly enhance the services provided not just to our passengers with visual and hearing disabilities, but to all passengers traveling on one of our 85 different routes throughout the region."

The $19.3 million project that Orbital began in May 2002 supported the installation of fully integrated system components on 750 fixed-route buses, 200 paratransit (Dial-A-Ride) vehicles and 60 support vehicles. Orbital provided its OrbCAD system to track and manage the day-to-day operations of the Phoenix area's transit vehicle fleet. The OrbCAD-based VMS solution includes radio, Computer Aided Dispatch/Automatic Vehicle Location (CAD/AVL), automatic passenger counting, next stop announcement and the ability to easily integrate future enhancements such as traffic signal prioritization. Also provided were 20 Advanced Traveler Information System (ATIS) signs throughout the city, offering Valley Metro RAPID riders real-time bus arrival information at their stops. In spite of a harsh environment and bright light conditions, Orbital was able to deliver a robust, easy-to-read sign that resides in a custom-designed enclosure. The VMS is engineered to be scalable to accommodate any future growth of the Valley Metro agencies.

"The Orbital's TMS system provides reliable communications, data messaging and schedule adherence that has helped us better manage our resources," said Mr. John Kelley, VMS Project Manager. Mr. Tom Drozt, Project Supervisor for the City of Phoenix added, "Having the ability to analyze fleet management, mechanical and operational issues and much more is a phenomenal tool that we use to continually improve our performance."

Mr. David Kachemov, Vice President and General Manager of Orbital's TMS division, said, "The TMS/Valley Metro team has developed a first class transit system that will be able to expand as the Phoenix Metro area grows. The ability of multiple agencies to successfully work together in developing the process and operational structure necessary for system deployment while sharing a common radio and fixed-end infrastructure is a real tribute to the Valley Metro organization."

About Orbital TMS

Orbital TMS is the country's leading supplier of satellite-based Automatic Vehicle Location (AVL) systems for the expanding Intelligent Transportation Systems market. Orbital's AVL systems are used by 55 transit and state agency customers in the U.S. and internationally, with units installed, or scheduled to be installed, on approximately 26,000 buses and similar public-transit vehicles. More information about Orbital TMS can be found at http://www.tms-online.com

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 Sciences Corporation can be found at http://www.orbital.com

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

    SOURCE: Orbital Sciences Corporation