Third Satellite in BSAT-2 Series to Provide Video Distribution
                              Services For Japan

         60-Day Post-Launch Checkout Procedure Now Underway Prior To
                        In-Orbit Delivery to Customer

DULLES, Va., June 12 /PRNewswire-FirstCall/ -- Orbital Sciences Corporation (NYSE: ORB) announced today that the BSAT-2c geosynchronous orbit (GEO) communications satellite the company built for Broadcasting Satellite System Corporation (B-SAT) of Japan was successfully launched aboard an Ariane 5 rocket on Wednesday, June 11, 2003. The mission originated from the Arianespace launch complex in Kourou, French Guiana at approximately 6:38 p.m. (EDT). The BSAT-2c satellite was deployed into a transfer orbit about 35 minutes later. Initial communications with the satellite have been established and it is performing as expected in the early stages of the mission. The BSAT-2c satellite is the third spacecraft Orbital has built for B-SAT and the sixth GEO spacecraft Orbital has launched, each of them carried aboard an Ariane rocket.

Over the next several days, BSAT-2c will perform a series of orbit raising "burns" of its on-board rocket motor to achieve a circular orbit approximately 22,300 miles above the Earth. For several weeks afterward, a team of Orbital and B-SAT engineers will conduct a comprehensive series of tests to ensure the readiness of the spacecraft for final hand-over to B-SAT, which is currently scheduled to occur in mid-August.

The BSAT-2c satellite will operate in Ku-band frequencies from its orbital location at 110 degrees East longitude. The spacecraft is optimized for a 10- year design life and will provide additional capacity for B-SAT's satellite network over Japan.

In the past several years, Orbital has firmly established itself as a major supplier in the world market for GEO communications and broadcasting satellites. The company's GEO satellites are based on the STAR(TM) family of smaller GEO satellite platforms, which are able to accommodate most types of commercial communications payloads. For many applications, the STAR design is an attractive alternative to the industry's larger, more costly GEO satellites. The STAR satellites are smaller and significantly less expensive to manufacture and launch. They are an ideal fit for customers in the early stages of building their business or established companies like B-SAT that wish to replace or add incremental capacity to their network.

About Orbital

Orbital develops and manufactures small space systems for commercial, civil government and military customers. The company's primary products are spacecraft 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

    Note to editors:

    * A high-resolution (300+ d.p.i.) artist rendering of a BSAT-2 series
      satellite in orbit is available on Orbital's web site at:
      http://www.orbital.com/NewsInfo/Images/GEO/

    * A Fact Sheet on the BSAT-2 series satellites is also available on
      Orbital's web site at: http://www.orbital.com/NewsInfo/Publications/

CONTACT: Barron Beneski, Public and Investor Relations, of Orbital Sciences Corporation, +1-703-406-5528, or Beneski.barron@orbital.com.

SOURCE  Orbital Sciences Corporation
    -0-                             06/12/2003
    /CONTACT:  Barron Beneski, Public and Investor Relations, of Orbital
Sciences Corporation, +1-703-406-5528, or Beneski.barron@orbital.com/
    /Web site:  http://www.orbital.com http://www.orbital.com/NewsInfo/Images/GEO http://www.orbital.com/NewsInfo/Publications/
    (ORB)

CO:  Orbital Sciences Corporation; Broadcasting Satellite System Corporation
ST:  Virginia, Japan
IN:  ARO CPR TLS
SU:


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