DULLES, Va.June 26, 2003--

Mission Was 34th Flight of Air-Launched Pegasus Rocket and Its 20th Consecutive Success

Orbital Sciences Corporation (NYSE:ORB) announced that earlier today, it successfully launched the company-built OrbView-3 high-resolution imaging satellite into its targeted orbit aboard the company's Pegasus(R) rocket. The OrbView-3 satellite was accurately delivered into an initial "parking" orbit and, over the next several weeks, Orbital engineers will command the satellite to use its onboard propulsion system to reach its final circular operational orbit of 470 kilometers above the Earth, inclined at 97 degrees to the equator. Orbital designed, developed, built and tested the 304-kilogram OrbView-3 satellite for Orbital Imaging Corporation (ORBIMAGE) at the company's Dulles, Virginia satellite manufacturing facility.

The powered flight sequence for the OrbView-3 mission took about 10 minutes, from the time the Pegasus rocket was released from its L-1011 carrier aircraft at approximately 2:55 p.m. (EDT) to the time that the satellite was deployed into orbit. Preliminary information indicates that the OrbView-3 satellite is working as planned in the early stages of its mission.

"We are very pleased with the results of the Pegasus launch and with the early indications that the OrbView-3 satellite is operating as expected," said Mr. David W. Thompson, Orbital's Chairman and Chief Executive Officer. "We look forward to delivering a highly-capable satellite that will allow ORBIMAGE to provide its customers with world-class imagery products."

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 satellites 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

    SOURCE: Orbital Sciences Corporation