-- Second Successful Flight of Minotaur IV Extends Perfect Launch Record of Minotaur Rocket Family to 18 Missions ---- Launch of SBSS Block 10 System Supports Air Force's Ability to Track and Respond to Threats in Space --

DULLES, Va., Sep 26, 2010 (BUSINESS WIRE) -- Orbital Sciences Corporation (NYSE: ORB), one of the world's leading space technology companies, today announced that it successfully launched the U.S.Air Force's Space Based Space Surveillance (SBSS) Satellite, also known as SBSS Block 10, aboard a Minotaur IV rocket. The launch, which took place on Saturday, September 25, 2010 from Vandenberg Air Force Base (VAFB) in California, extends Orbital's record of launches with the Minotaur family of rockets to a perfect 18 successes out of a total of 18 missions.

The Minotaur IV rocket lifted off from Space Launch Complex-8 at VAFB at 9:41 p.m. (PDT). The rocket flew an orbital trajectory downrange over the Pacific Ocean and delivered the SBSS satellite to the desired separation conditions.

The Minotaur IV launch vehicle is based on decommissioned Peacekeeper rocket motors that Orbital has upgraded and integrated with modern avionics and other subsystems to produce a cost-effective launcher based on flight-proven hardware. The launch of the SBSS satellite marks the first orbital mission for the Minotaur IV, which currently has a manifest of eight missions over the next several years.

"The second successful Minotaur IV flight, and the first orbital mission for the vehicle, continues the strong and growing tradition of mission success of the Minotaur rocket family. We are proud to support the U.S. Air Force with the next generation of the Minotaur family for the government's Space Based Space Surveillance satellite program," said Mr. Ron Grabe, Orbital's Executive Vice President and General Manager of its Launch Systems Group. "With two successful launches, we are confident the Minotaur IV can provide the flexibility and reliability the Air Force demands."

Orbital has eight subsequent Minotaur IV launches scheduled, the next of which will launch the STP-26 mission, which is a small developmental satellite for the Air Force. The mission will originate from the Alaska Spaceport launch complex in Kodiak, Alaska.

About Minotaur IV

The Minotaur IV space launch vehicle leverages the flight-proven heritage of Orbital's Minotaur I, Pegasus and Taurus space launch vehicles to provide a reliable, capable and cost-effective space launcher. Minotaur IV utilizes three government-furnished solid rocket motors from decommissioned Peacekeeper ICBMs and, in certain configurations, a commercial solid rocket upper stage. Building on long experience of launch systems with over 50 flights of each core stage, Minotaur IV is capable of launching payloads up to approximately 4,000 lbs. (1,830 kgs.) to low Earth orbit.

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

SOURCE: Orbital Sciences Corporation

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