DULLES, Va.March 13, 2006--Orbital Sciences Corporation (NYSE:ORB) announced today that its Transportation Management Systems (TMS) division has been awarded a contract valued at $8.2 million by the Maryland Transit Administration (MTA) in Baltimore, Maryland. Under the new contract award, Orbital will provide a "Next Vehicle Arrival" system for 200 bus stops and upgrade the MTA's existing Computer Aided Dispatch and Automated Vehicle Location (CAD/AVL) capabilities for its fleet of 800 vehicles. Orbital installed the original MTA fleet tracking system in 1996.

The new Next Vehicle Arrival system is one element of MTA's commitment to improve the convenience and ease of use of public transit in the Baltimore area. The system will provide real-time bus arrival information at 200 MTA bus stops and transit centers in the Baltimore region. The Next Vehicle Arrival system uses Orbital's proven Global Positioning Satellite technologies to determine the exact location of each MTA bus. The arrival time is then transmitted to an electronic information sign at each of the bus stops, informing MTA's riding public when their bus will be arriving. The system also includes the ability to present additional information to passengers, such as weather conditions or security alerts.

Orbital is also providing a comprehensive upgrade to the MTA's existing SmartTrack fleet management system. The upgrade will modernize the current radio communication and CAD/AVL system in addition to providing the Next Vehicle Arrival system. Orbital's SmartTrack CAD/AVL is scalable and is able to accommodate future growth of the MTA fleet. Originally installed on only a portion of the fleet, the CAD/AVL functionality will now be incorporated into MTA's entire fleet. The increased features and capabilities of the upgrade will provide MTA dispatchers and supervisors with improved fleet management, increased situational awareness and the ability to respond to incidents more expeditiously.

Mr. A. David Kachemov, Senior Vice President and General Manager of Orbital's TMS division, said, "The Orbital TMS team appreciates the opportunity to continue its long-term relationship with the MTA. These enhancements to the MTA's existing SmartTrack system demonstrate our commitment to support our existing customers and to enhance their investment."

Orbital TMS is the country's leading supplier of satellite-based Automatic Vehicle Location 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 vehicles. More information about Orbital TMS can be found at http://www.tms-online.com

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 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