DULLES, Va., June 19 /PRNewswire/ -- Orbital Sciences Corporation (NYSE: ORB) announced today that the National Aeronautics and Space Administration (NASA) has decided to postpone the launch of its High Energy Spectroscopic Imaging (HESSI) satellite aboard the company's Pegasus XL space launch vehicle. NASA has elected to delay the HESSI mission in order to allow time for review of the analysis being performed by the X-43A Mishap Review Board.

As a result of the delay in the launch schedule, Orbital will ferry the air-launched Pegasus rocket from Florida back to the company's facility at Vandenberg Air Force Base in California. This is necessary to permit replacement of the rocket's flight termination batteries that will exceed their approved life cycle as a result of the delay. Orbital will maintain overall flight readiness for HESSI in order to preserve the ability to launch on short notice.

Orbital is one of the world's leading manufacturers of low-cost space systems, including satellites, launch vehicles and sensors and electronics systems. Orbital is also involved with satellite-based networks that provide wireless data communications and high-resolution Earth imagery to customers all around the world.

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

CONTACT: Media: Barron Beneski, 703-406-5528, or
beneski.barron@orbital.com; or Investors: Timothy Perrott, 703-406-5997, or
perrott.tim@orbital.com, both of Orbital Sciences Corporation
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SOURCE Orbital Sciences Corporation

CONTACT: Media: Barron Beneski, 703-406-5528, or beneski.barron@orbital.com; or Investors: Timothy Perrott, 703-406-5997, or perrott.tim@orbital.com, both of Orbital Sciences Corporation/