DULLES, Va., June 5 /PRNewswire/ -- Orbital Sciences Corporation (NYSE: ORB) announced today that the launch of its Pegasus XL rocket carrying NASA's High Energy Solar Spectroscopic (HESSI) satellite has been postponed. Orbital is supporting a NASA-led investigation to determine if there may be any associated technical issues between the X-43A/Hyper-X launch failure at Edwards Air Force Base on Saturday, June 2, and the Pegasus XL vehicle awaiting launch at Cape Canaveral Air Force Base, Florida. A new launch date for the HESSI mission, originally scheduled for June 7, will be announced once NASA and Orbital have completed the investigation.

Orbital is one of the world's leading manufacturers of low-cost space systems, including satellites, launch vehicles and electronics and sensors 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: Tim Perrott, 703-406-5997 or
perrott.tim@orbital.com, both of Orbital Sciences Corporation.
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SOURCE Orbital Sciences Corporation

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