-- Spacecraft for Telenor of Norway will be the First
   Orbital-Built GEO Communications Satellite Launched Aboard an ILS
                           Proton Rocket --

DULLES, Va.Feb. 8, 2008--Orbital Sciences Corporation (NYSE:ORB), the world leader in smaller-sized commercial geosynchronous (GEO) communications satellites, is in final preparations for the launch of the THOR 5 satellite. Orbital designed, built and tested the THOR 5 spacecraft at its Dulles, Virginia satellite manufacturing facility for Telenor Satellite Broadcasting of Norway. The launch of the THOR 5 satellite from the Baikonur Cosomodrome in Kazakhstan is currently scheduled to take place on Sunday, February 10 at 6:33 a.m. (EST). The spacecraft will be launched directly into geosynchronous orbit aboard a Proton launch vehicle provided by International Launch Services (ILS).

"Our team is very excited to be in the final phase of preparing the THOR 5 spacecraft for its launch and deployment," said Senior Vice President Christopher Richmond, head of Orbital's GEO communications satellite programs. "This mission consists of two 'firsts' for Orbital. THOR 5 is the first satellite we have built for Telenor and we are looking forward to supporting them for many years to come. This mission will also be the first time one of our GEO communications satellites has been directly injected into geosynchronous orbit using an ILS Proton rocket."

About THOR 5

The THOR 5 satellite is based on Orbital's STAR-2 platform. It will provide Ku-band fixed telecommunications and direct-to-home television broadcasting services from Telenor's 1-degree West Longitude orbital location. The THOR 5 satellite will have 24 transponders with three times more payload power (3.6 kilowatts) than the current THOR II satellite, which it will replace. THOR 5 will weigh approximately 1,960 kg at launch and will improve Telenor's service coverage in the Nordic countries and Europe.

Orbital's commercial satellite business has experienced rapid growth over the past several years. In addition to THOR 5, the company currently has eight other commercial GEO satellites and five science and defense spacecraft in various stages of design, production and testing at its Dulles, Virginia satellite manufacturing facility. To accommodate this rapid rate of growth, Orbital has completed an expansion of its manufacturing plant that, together with other facility improvements, has increased its manufacturing throughput capacity by over 30% as compared to one year ago.

About Orbital

Orbital develops and manufactures small rockets and space 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.

    Note to Editors:

    --  A high-resolution image of the THOR 5 satellite is available
        on Orbital's web site at:
        SatelliteSpaceSystems/index.shtml (Due to its length, this URL
        may need to be copied/pasted into your Internet browser's
        address field.  Remove the extra space if one exists.)

    --  Additional THOR 5 mission information, including
        high-resolution images of the launch, will be available at:

    CONTACT: Orbital Sciences Corporation
             Barron Beneski, 703-406-5528
             Public and Investor Relations

    SOURCE: Orbital Sciences Corporation