DULLES, Va.June 24, 2003--

    Mission Will be 34th Flight of Company's Air-Launched Rocket

Orbital Sciences Corporation (NYSE:ORB) today announced that it is in final preparations to launch the OrbView-3 high-resolution imaging satellite that the company designed and built for Orbital Imaging Corporation (ORBIMAGE) aboard a Pegasus(R) rocket later this week. The launch is currently scheduled to take place on Thursday, June 26, 2003 and will originate from Vandenberg Air Force Base (VAFB) in California. The available launch window for the OrbView-3 mission extends from 2:50 p.m. to 3:04 p.m. (EDT). This operational schedule is subject to the completion of final pre-launch activities, as well as acceptable weather conditions at VAFB at the time of the launch.

The powered flight sequence for the OrbView-3 mission will take approximately 10 minutes, from the time the Pegasus rocket is released from the L-1011 carrier aircraft to the time that the satellite is deployed into orbit. Orbital plans to launch the 304-kilogram OrbView-3 spacecraft into an initial "parking" orbit, from which the spacecraft will be maneuvered into its final operational orbit 470 kilometers above the Earth, inclined at 97 degrees to the equator.

About Pegasus

Pegasus is the world's leading launch system for the deployment of small satellites into low-Earth orbit. Its patented air-launch system, in which the rocket is launched from beneath Orbital's "Stargazer" L-1011 carrier aircraft over the ocean, reduces cost and provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements. Pegasus is the world's only small launch vehicle to have earned NASA's Category 3 certification, which allows the U.S. space agency to launch its most valuable payloads aboard the rocket. The Category 3 certification is achieved through a long-term record of highly reliable launch services, such as the current record of 19 consecutive successful Pegasus missions carried out since 1997.

The OrbView-3 mission will be the 34th flight of the Pegasus rocket and the third of four planned missions in 2003. Earlier this year, Orbital successfully launched two company-built scientific satellites for NASA in separate missions. In January, Orbital launched NASA's SORCE satellite aboard Pegasus and, in April, another Pegasus rocket delivered NASA's GALEX satellite into orbit. Following the OrbView-3 mission, Orbital plans to launch the SciSat satellite for NASA/Kennedy Space Center and the Canadian Space Agency later this summer.

About the OrbView-3 Satellite

Orbital designed, developed, built and tested the OrbView-3 spacecraft at the company's satellite manufacturing facility in Dulles, Virginia. OrbView-3 will be one of only a few commercial spacecraft with the capability of providing high-resolution imagery from space to government and commercial customers. The high-resolution digital imaging instrument aboard the OrbView-3 spacecraft will acquire one-meter resolution panchromatic (black and white) and four-meter resolution multispectral (color) imagery. ORBIMAGE will provide this imagery to customers around the world for a wide-range of applications in the commercial, government and consumer markets. With the ability to image virtually anywhere in the world within three days, ORBIMAGE has established a global distribution network to capture, process and deliver up-to-date basic imagery, as well as high-resolution value-added products, through its own capabilities and a network of imagery distribution partners.

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.

    Note to Editors:

--  Orbital and ORBIMAGE will provide live mission updates, beginning
    at 1:00 p.m. (EDT) on launch day, as well as a mission overview
    and high-resolution photos of the OrbView-3 satellite and Pegasus
    rocket. The OrbView-3 Mission Central web page can be found at:
    http://www.orbital.com/NewsInfo/MissionUpdates/ov3_central.html 

    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703/406-5528
             beneski.barron@orbital.com

    SOURCE: Orbital Sciences Corporation