DULLES, Va.Sept. 15, 2006--

    Capital Metro to Utilize Orbital's Latest Vehicle Location and
       Passenger Information Technologies for Management of Bus,
                      Paratransit and Rail Fleets

Orbital Sciences Corporation (NYSE:ORB) announced today that its Transportation Management Systems (TMS) division has been awarded a $12.5 million contract by the Capital Metropolitan Transportation Authority (Capital Metro) in Austin, Texas. Under the new contract, Orbital will provide its latest Computer Aided Dispatch (CAD) and Automatic Vehicle Location (AVL) system, known as OrbCAD XP. The company will also supply Capital Metro with a suite of real-time and analytical tools that will assist in the day-to-day management of the 526-vehicle fleet of local, express and paratransit bus services, as well as its forthcoming commuter rail service.

"With the installation of the new Orbital CAD/AVL system, Capital Metro is seizing the opportunity to further increase services to our customers while holding down our operating costs," stated Fred Gilliam, President and Chief Executive Officer of Capital Metro. "We will implement real-time schedule information at new rail stations and park and ride lots to benefit riders throughout the Capital Metro service area."

Orbital will deliver the system in a phased approach. The company will begin with the installation of the dispatch system and onboard equipment for Capital Metro's paratransit service, known as Special Transit Services (STS). Later, Capital Metro's new Rapid express bus service, commuter rail service and fixed-route bus services will be equipped.

Orbital will provide several other new features for all modes of the Capital Metro system. Capital Metro's STS vehicle operators will be able to utilize custom directional information to better locate passenger pick up and drop off locations. Additionally, the module will allow the opportunity to update the STS operator's manifest, or schedule, throughout the day as changes are made to passenger pick up and drop off times.

Mr. A. David Kachemov, Senior Vice President and General Manager of Orbital TMS, said, "Orbital is eager to begin work with Capital Metro to install the systems that will help further its mission to the people of Austin. With our innovative products and our dedicated team of professionals, Orbital will be able to deliver a system that benefits the Capital Metro team as well as the passengers of the entire bus and rail systems. Plus, the OrbCAD XP system's open architecture will allow Capital Metro to add new features in the future as Austin continues to grow."

About Orbital TMS

Orbital TMS is a leading integrator of products for fleet and workforce management, mobile data communications, data management and advanced traveler information systems. TMS provides integrated CAD and AVL solutions for sixty public transit and state agency customers in the U.S. and internationally, with units installed or scheduled to be installed on approximately 27,500 vehicles. More information about Orbital TMS can be found at http://www.orbitaltms.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-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
             Public and Investor Relations:
             Barron Beneski, 703-406-5528

    SOURCE: Orbital Sciences Corporation