DULLES, Va.Sept. 12, 2005--Orbital Sciences Corporation (NYSE:ORB) announced today that its Transportation Management Systems division (Orbital TMS) has been awarded a $4.4 million contract by Intercity Transit of Olympia, WA to provide an Advanced Communications System (ACS) to manage a fleet of 85 vehicles. The vehicles will include 54 fixed-route buses, 25 Dial-A-Lift vehicles and six maintenance vehicles. Orbital's ACS will provide a radio communications system that is fully integrated with the company's OrbCAD product, which features Computer Aided Dispatch and Automated Vehicle Location capabilities.

Mr. Roger Dean, Development Director for Intercity Transit stated, "The ACS is designed to support Intercity Transit's commitment to high-quality service delivery by improving communications reliability and efficiency between our dispatchers and operators. This will help both our fixed route and Dial-A-Lift operations and, ultimately, enhance service to our many customers."

With Orbital's ACS deployment, Intercity Transit expects to realize both reduced operating costs and improved service to its riders. Intercity Transit will collect and analyze data from actual operations and modify its schedules and travel times to improve on-time performance. The ACS integrates both fixed-route and on-demand response for transit services on a new multi-site communications system. Orbital's ACS enhances public safety and security and improves dispatcher-to-driver communications to facilitate the real-time decision making process that is critical to enhanced schedule performance.

Mr. David Kachemov, Vice President and General Manager of Orbital's TMS division, said, "Orbital TMS is committed to working with Intercity Transit to seamlessly implement this state-of-the-art fleet management and communications system. Of particular importance is the ability of our system to be scalable, with the flexibility to support our customer's growth. As Intercity Transit operations expand, the ACS system is adaptable enough to accommodate a larger scale implementation."

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 mass-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