ORBITAL SUCCESSFULLY LAUNCHES PATRIOT TARGET VEHICLE FOR MISSILE DEFENSE TEST

ORBITAL SUCCESSFULLY LAUNCHES PATRIOT TARGET VEHICLE FOR MISSILE DEFENSE TEST

-- Company Conducts Second "PTV Juno" Mission for U.S. Air Force Space
and Missile Systems Center --

(Dulles, VA 2 March 2011) - Orbital Sciences Corporation (NYSE: ORB) announced today that it successfully launched a Patriot Target Vehicle (PTV) under a direct contract with the U.S. Air Force Space and Missile Systems Center (SMC) Space Development and Test Directorate (SD). The PTV served as an intercept target for the Lower Tier Project Office Patriot missile defense system. The PTV was launched on March 2, 2011 from Fort Wingate Launch Complex-96 into White Sands Missile Range (WSMR) in New Mexico. It flew a southerly trajectory over New Mexico into WSMR and was intercepted by the Patriot Missile Segment Enhancement (MSE) interceptor system during reentry. This PTV, known as Juno, was the second of two targets Orbital is under contract to launch in support of the Patriot MSE test and evaluation program.

"We are very pleased to support the U.S. Air Force and the Lower Tier Projects Office with a second successful target launch, culminating in a positive intercept indication," said Mr. Ron Wiley, Senior Vice President of Suborbital Targets Programs at Orbital. "We look forward to supporting future tests for the Space Development and Test Directorate with the PTV, which has demonstrated its performance as a reliable test platform for future SD missions and Patriot engagements."

Orbital developed the PTV target vehicle over a two and a half year period according to specifications that require the vehicle to have selectable reentry dynamic performance. The PTV Juno rocket relied heavily on flight-proven designs from other Orbital launch vehicles, such as the Medium Range Target, Storm target and Pegasus space launch vehicles.

Orbital is one of the United States' most experienced developers and operators of missile defense-related launch vehicles. The company supports virtually all of the country's major missile defense programs with highly-reliable and cost-effective target vehicles. In addition to the Patriot program, Orbital's target vehicles are used to test Aegis BMD, MDA's Ground-based Midcourse Defense system (GMD) and THAAD systems. Orbital also produces the "Coyote" ramjet-powered sea-skimming supersonic naval target vehicle used to test the U.S. Navy's ship self-defense systems.

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 www.orbital.com

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