-- Satellite Is Performing as Expected Early in a 15-Year Service Lifetime --
-- Spacecraft Is Second of Five Commercial Satellites Built by Orbital Scheduled To Be Launched in 2010 --

DULLES, Va., Apr 26, 2010 (BUSINESS WIRE) --Orbital Sciences Corporation (NYSE: ORB), one of the world's leading space technology companies, today announced that the SES-1 satellite, built by the company for SES WORLD SKIES, was successfully launched into orbit aboard an International Launch Services (ILS) Proton rocket from the Baikonur Cosmodrome in Kazakhstan. The mission began on Saturday, April 24, with the lift-off of the Proton space launch vehicle at 7:18 a.m. (EDT). The satellite successfully separated from the Proton rocket's Breeze M upper stage eight hours and 58 minutes after liftoff.

Mr. Christopher Richmond, Orbital's Senior Vice President and head of its communications satellite business unit, said, "Following the launch of the SES-1 satellite on Saturday, we are very pleased with the progress of the mission so far. The ILS Proton accurately delivered the satellite into its intended orbit and the spacecraft has been performing nominally since its separation from the launch vehicle. Together with the engineering team from SES WORLD SKIES, we have begun the process of in-orbit testing that will be carried out over the next several weeks."

Mr. Richmond added, "With the launch of SES-1, the second company-built commercial communications satellite to be launched in 2010, we are well into a very busy year during which a total of five geosynchronous orbit communications satellites are scheduled to be delivered and launched for customers around the world."

Orbital designed, built and tested the SES-1 spacecraft at the company's satellite manufacturing facility in Dulles, VA. The state-of-the-art satellite will replace SES' existing AMC-2 and AMC-4 spacecraft at the 101 degrees West longitude orbital position. The satellite carries 24 C-band transponders as well as 24 Ku-band transponders and has been designed to provide in-orbit services for 15 years. The SES-1 satellite is based on Orbital's Star 2.4 platform and will generate approximately five kilowatts of payload power.

Orbital is also building two other satellites for SES WORLD SKIES. Currently, the SES-2 and SES-3 spacecraft are in production and testing at the company's Dulles, VA facilities. Together, the three SES spacecraft will deliver full 50-state coverage of the U.S. in both C- and Ku-band frequencies from their strategically important orbital locations.

About SES

SES (Euronext Paris and Luxembourg Stock Exchange: SESG) wholly owns the market-leading satellite operators SES ASTRA and SES WORLD SKIES, and participations in Ciel in Canada, QuetzSat in Mexico as well as in satellite infrastructure start-up O3b Networks. SES provides outstanding satellite communications solutions via a global fleet of 41 satellites in 26 orbital locations. For further information: www.ses.com

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 exploration 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 U.S. Government agencies and laboratories. More information about Orbital can be found at http://www.orbital.com

Note to Editors: High resolution images of the SES-1 satellite are available on Orbital's web site at: http://www.orbital.com/NewsInfo/ImagesMultimedia/Images/SatelliteSpaceSystems/index.shtml

SOURCE: Orbital Sciences Corporation

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