-- NASA's Orbiting Carbon Observatory Satellite Does Not Achieve Orbit --

DULLES, Va.Feb. 24, 2009-- Orbital Sciences Corporation (NYSE:ORB) announced today that the launch of its Taurus XL rocket, which lifted off at 4:55 a.m. (EST) from Vandenberg Air Force Base, CA., carrying the company-built Orbiting Carbon Observatory satellite for NASA, did not achieve orbit. Preliminary indications are that the payload fairing on the Taurus XL vehicle failed to separate. The fairing is a clamshell structure which encapsulates the satellite as it travels through the atmosphere.

Orbital will immediately convene an internal failure investigation board that will include representatives from the company and NASA to determine the cause of today’s launch failure. Orbital believes that it is likely that it gathered sufficient data during the flight that will enable the company to identify the cause of the failure.

Source: Orbital Sciences Corporation

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