-- Company Ready to Deliver Spacecraft Just Over 22 Months from Contract Start --

Orbital Sciences Corporation (NYSE:ORB) has completed final testing on the SES New Skies NSS-9 commercial communications satellite, the company announced today. Orbital’s engineering team completed all pre-shipment procedures late last week for the NSS-9 satellite, which will be stored at the company’s Dulles, VA facilities until the company is notified of the launch date. Orbital stated that the spacecraft was designed, manufactured and tested in approximately 22 months from the start of the contract to the completion of the pre-shipment review.

“We are very pleased to be able to complete the NSS-9 spacecraft on such an efficient production schedule,” said Mr. Michael Larkin, Orbital’s Executive Vice President and General Manager of its Space Systems Group. “Utilizing the lean manufacturing techniques and other efficient production and testing processes that we have implemented, the NSS-9 satellite program displays the kind of responsiveness to our customers’ needs that our team is capable of delivering to maintain our industry-leading delivery schedule.”

Based on Orbital’s STAR-2™ satellite bus, NSS-9 carries 28 active C-band transponders and features three beams that can be interconnected on a transponder-by-transponder basis: a global beam providing coverage of the entire earth visible from its 183 degrees East longitude orbit slot, another beam covering Australia, Indonesia, the Philippines, Japan, China, Korea and the Pacific Islands, and a third beam providing coverage and connectivity to the U.S., Hawaii and Polynesia.

Orbital’s geosynchronous-orbit (GEO) commercial communication business remains robust, with four new orders so far this year, including the AMC-1R satellite for SES Americom, the Koreasat-6 satellite for KT Corporation (in partnership with Thales Alenia Space), and the IS-18 satellite for Intelsat. Excluding NSS-9, Orbital currently has ten other commercial communications satellites in various stages of design and production for launches between 2009 and 2010. Two other Orbital-built GEO satellites were launched this year, THOR 5 for Telenor of Norway and AMC-21, the first of five satellites ordered by SES Americom.

About Orbital

Orbital develops and manufactures small- and medium-class rockets and space systems for commercial, military and civil government customers. The company’s primary products are satellites and launch vehicles, including low-Earth orbit, geosynchronous-Earth orbit and planetary spacecraft for communications, remote sensing, scientific and defense missions; human-rated space systems for Earth-orbit, lunar and other 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 provides satellite subsystems and space-related technical services to government agencies and laboratories.

More information about Orbital can be found at http://www.orbital.com

Note to Editors:

• High-resolution images of the NSS-9 GEO satellite is available at: http://www.orbital.com/NewsInfo/ImagesMultimedia/Images/Satell iteSpaceSystems/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.)

Orbital Sciences Corporation
Barron Beneski, 703-406-5528
Public and Investor Relations
beneski.barron@orbital.com