-- Mission Marks 15th Consecutive Success for Minotaur Launch Vehicles --(Dulles, VA 25 September 2008) -- Orbital Sciences Corporation (NYSE: ORB)announced today that its Minotaur II+ rocket was successfully launched forthe U.S. Air Force Space and Missile Systems Center (SMC) in support of theMissile Defense Agency (MDA) Near-Field Infrared Experiment (NFIRE). Themission was conducted on Tuesday, September 23, 2008, from Vandenberg AirForce Base (VAFB), California. The program office responsible for Minotaurlaunch vehicles is the Launch Test Squadron of the Space Development andTest Wing (SDTW) at Kirtland Air Force Base, New Mexico. This mission wasthe eighth for the Minotaur II Target Launch Vehicle (TLV) and the 15th forthe Minotaur family, all of which have been successful.The launch originated from VAFB at approximately 11:57 p.m. (PDT) onSeptember 23. Final targeting for the mission was uploaded to the rocketapproximately one and a half hours prior to launch. The vehicle wassuccessfully launched within a one-second launch window, which was requiredto meet the mission’s precise targeting requirements. The vehicle’s firsttwo solid rocket motors burned for approximately two minutes, at which timethe vehicle entered into a coast phase lasting over one minute. After itscoast period, the third and final stage ignited, placing the vehicle oncourse to burn through a precise aim point at an exact time nearly 250 kmabove the Pacific Ocean. The vehicle was being observed by the NFIREsatellite and a variety of Missile Defense Agency sensors deployed acrossthe Pacific region. At the point of closest approach, the Minotaur targetvehicle and NFIRE satellite were within several kilometers of each other.In addition to conducting this Minotaur II+ TLV mission, Orbital alsolaunched the NFIRE satellite in April 2007 aboard a Minotaur I space launchvehicle in a mission conducted from NASA’s Wallops Flight Facility inEastern Virginia. Orbital also conducted an earlier Minotaur II+ TLVlaunch that was observed by the NFIRE satellite last year.Minotaur II+ is an upgraded version of the reliable and proven Minotaur IIvehicle, yielding a more capable vehicle for future applications. Themajor upgrades include a higher performing third stage and largerstructures. The new stage and structures enable the launch of larger andheavier payloads or reentry vehicles. The previous Minotaur II+ missionwas launched in August 2007 and met all customer requirements, alsodemonstrating precise timing and targeting accuracy. The flight involved anumber of first flight items, including a new Pierce Point Guidancealgorithm and demonstration of a launch minus 90-minute target point uploadto the flight computer, capabilities that have Operationally ResponsiveSpace (ORS) applications.Orbital is one of the country’s leading suppliers of launch vehicles usedin missile defense and other military applications. In addition to numerousconfigurations of target vehicles, Orbital is also designing and buildingthe interceptor boosters for two major missile defense programs, includingthe Ground-based Midcourse Defense (GMD) system, which uses the company’sthree-stage Orbital Boost Vehicle (OBV), and the Kinetic EnergyInterceptors (KEI) program, which is designed to intercept and destroyenemy missiles in the early boost phase of flight. These interceptors arepart of a layered missile defense system for defending the nation, ourarmed forces and our allies against ballistic missile attacks.About Orbital’s Minotaur Product LineThe Minotaur product line consists of the only proven launch vehiclescurrently capable of supporting the U.S. Department of Defense’s evolvingORS space launch requirements, as well as long-range target delivery formissile defense and technology demonstration missions. They arespecifically designed to be capable of launching from all major U.S.spaceports, including government and commercial launch sites in Alaska,California, Florida and Virginia. In addition, the minimal amount ofspecialized ground infrastructure that is required to support Minotaurlaunches enable them to be employed at other U.S. launch sites. Orbital’suse of standardized avionics and subsystems, mature processes andexperienced personnel make Minotaur rockets both reliable andcost-effective for U.S. government customers.Orbital’s Minotaur product line currently consists of the followingconfigurations:Minotaur I - The initial member of the Minotaur family, the Minotaur I is afour-stage space launch configuration that can place up to 1,300 lbs. intolow-Earth orbit. It was originally launched in January 2000 and carries aperfect seven-for-seven mission success record. The next planned MinotaurI mission is the launch of the TacSat-3 spacecraft currently scheduled forthe fourth quarter of 2008.Minotaur II - A three-stage suborbital rocket, the Minotaur II is used as atarget vehicle for testing U.S. missile defense systems and relatedmissions. This configuration carries a perfect eight-for-eight missionsuccess record since its first flight in June 2000.Minotaur III - A three-stage suborbital rocket, Minotaur III can deliversuborbital technology demonstration payloads of up to 6,500 lbs. or serveas a target vehicle for testing U.S. missile defense systems and similarmissions.Minotaur IV - A heavier-lift four-stage space launch vehicle using retiredPeacekeeper rocket motors, the Minotaur IV is capable of launchingsatellites weighing up to 3,800 lbs. into low-Earth orbit. The firstMinotaur IV mission is currently in final production to launch a satellitefor the U.S. Air Force in early 2009. A configuration with increasedperformance, Minotaur IV+, is also under contract for an initial launch inlate 2009.