— Launch of NASA Astrophysics Satellite to Originate from Equatorial Range Following Trans-Pacific Flight of “Stargazer” Carrier Aircraft with Pegasus Rocket —

— Orbital-Built NuSTAR Satellite to Search for Black Holes in the Galaxy Following its Launch into Low-Earth Orbit –

(Dulles, VA 7 June 2012) — Orbital Sciences Corporation (NYSE: ORB), one of the world’s leading space technology companies, today announced that its Pegasus(R) rocket, which will launch NASA’s Nuclear Spectroscopic Telescope Array (NuSTAR) satellite, has arrived at its launch site in the mid-Pacific Ocean. Following a 4,200 nautical mile ferry flight that included a refueling stop at Hickam Air Force Base in Hawaii, Orbital’s “Stargazer” L-1011 carrier aircraft arrived at the Reagan Test Site airfield on Kwajalein Atoll in the Marshall Islands, where the NuSTAR launch will originate. The launch is currently scheduled for June 13 at approximately 11:30 a.m. (EDT), subject to final pre-launch testing and acceptable weather conditions at the time of launch.

During its mission, NuSTAR will use high-energy x-rays to detect black holes and other energetic phenomena in the universe with the purpose of expanding our understanding of the origins and destinies of stars and galaxies. NuSTAR will have more than one hundred times the sensitivity of previous instruments to detect black holes and will be the first focusing hard x-ray telescope in space.

For the NuSTAR mission, Orbital is providing the spacecraft platform, performing overall system integration, and conducting the launch operations with its Pegasus air-launched rocket, a comprehensive mission support combination that it has previously carried out for numerous successful NASA scientific missions such as the SORCE, GALEX, AIM and IBEX projects.

The NuSTAR satellite project is led by Dr. Fiona Harrison, the mission’s Principal Investigator from the California Institute of Technology (Caltech). It is part of NASA’s Small Explorer (SMEX) series that is managed by the Goddard Space Flight Center for NASA’s Science Mission Directorate. These low-cost, highly effective small satellite missions have enabled scientists to gather critical data about the Earth’s environment, the solar system and beyond. In addition to Caltech, NASA’s Jet Propulsion Laboratory (JPL) is one of Orbital’s key mission partners on the NuSTAR project.

Pegasus is the world’s leading launch system for the deployment of small satellites into low-Earth orbit. Its patented air-launch system, in which the rocket is launched from beneath Orbital’s “Stargazer” L-1011 carrier aircraft over the ocean, reduces cost and provides customers with unparalleled flexibility to operate from virtually anywhere on Earth with minimal ground support requirements. The NuSTAR launch from Kwajalein is an example of its unrivaled mission versatility. The launch of the NuSTAR satellite will be the 41st Pegasus mission since its introduction in 1990. It remains the world’s only small space launch vehicle that is certified with NASA’s Payload Risk Category 3, which the space agency reserves for its highest value space missions.

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