DULLES, Va.April 18, 2005--Orbital Sciences Corporation (NYSE:ORB) announced today that it has signed a new geosynchronous (GEO) communications satellite contract with PanAmSat Corporation (NYSE:PA). PanAmSat's new spacecraft will provide C- and Ku-band fixed telecommunications and direct-to-home television broadcasting services from a mid-Atlantic orbital location. The new satellite is the fourth one PanAmSat has purchased from Orbital since 2001 and is based on the company's STAR(TM) platform. PanAmSat previously purchased three C-band satellites for U.S. domestic communications services from Orbital, the first of which, Galaxy 12, was launched in 2003. Two sister satellites, Galaxy 14 and 15, are scheduled for launch later this year.

The new satellite, to be called PAS-11, will carry up to 18 active Ku-band transponders and 16 active C-band transponders. The satellite will generate approximately 4.5 kilowatts of electrical power and will weigh approximately 2,500 kg at launch. Delivery of the satellite is scheduled in the first quarter of 2007. The contract includes options for two additional spacecraft, each of which would generate approximately 4.7 kilowatts of power and would be delivered about 24 months after exercise of the contract options. Financial details of the contract were not released.

Commenting on the contract award, Dr. Ali Atia, head of Orbital's GEO communications satellite unit, said, "We very much appreciate the confidence PanAmSat has shown in Orbital by purchasing another satellite from us. We have demonstrated our capabilities and flexibility during the manufacturing of the three Galaxy spacecraft for PanAmSat over the last several years. We will continue to work in partnership with PanAmSat to ensure on-time delivery of the new spacecraft in order to assure an orderly transition of services for their customers."

Mr. Jim Frownfelter, PanAmSat's Chief Operating Officer, said, "We are very pleased to continue and expand our successful partnership with Orbital. Based on the outstanding working relationship that was established between our satellite teams during the design, development, manufacturing and test process for the first three spacecraft, we are moving forward with great confidence in our mixed fleet strategy that incorporates small satellites to allow us to better match capacity with customer demand."

Dr. Atia added, "This contract is further evidence of Orbital's increasing market position in the small class GEO satellite niches. With an advanced satellite design based on three-axis stabilization and significant power and mass margins over our nearest competitor in this class of spacecraft, we have clearly become the preferred supplier of satellites of this size."

The order from PanAmSat continues Orbital's growth in the market for small GEO communications satellites. Since the late 1990's, Orbital has received orders for 13 small GEO satellites. Including this most recent order, Orbital currently has seven small GEO satellites in various stages of design, manufacturing, testing and pre-launch preparations, and has options for three additional satellites that could be exercised in the future.

Orbital's highly successful GEO communications satellites are based on the company's STAR-1 and STAR-2 standard spacecraft platforms, which are able to accommodate most types of commercial communications payloads. For many applications, the lighter-weight, more-affordable Star design is an attractive alternative to the larger, more costly GEO satellites offered by other suppliers. Orbital's Star satellites are smaller and significantly less expensive to manufacture and launch. They are an ideal fit for established companies that require incremental capacity for their networks or for customers in the early stages of building their businesses.

About PanAmSat

Through its owned and operated fleet of 23 satellites, PanAmSat is a leading global provider of video, broadcasting and network distribution and delivery services. In total, the company's in-orbit fleet is capable of reaching over 98 percent of the world's population through cable television systems, broadcast affiliates, direct-to-home operators, Internet service providers and telecommunications companies. In addition, PanAmSat supports the largest concentration of satellite-based business networks in the U.S., as well as specialized communications services in remote areas throughout the world. For more information, visit the company's web site at www.panamsat.com.

About Orbital

Orbital develops and manufactures small space systems for commercial, civil government and military customers. The company's primary products are satellites and launch vehicles, including low-orbit, geostationary and planetary spacecraft for communications, remote sensing and scientific missions; ground- and air-launched rockets that deliver satellites into orbit; and missile defense boosters 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
             Beneski.barron@orbital.com

    SOURCE: Orbital Sciences Corporation