— New Order Represents the 27th Minotaur Rocket Purchased Since Program Start in 1997 —

— ORS-3 Enabler Mission Will be 5th Minotaur I Launch from Wallops Island, Virginia —

(Dulles, VA 3 April 2012) – Orbital Sciences Corporation (NYSE: ORB) announced today that the U.S. Air Force has exercised an option order for a Minotaur I space launch vehicle to support the ORS-3 “Enabler” mission for the Operationally Responsive Space (ORS) Office of the Department of Defense. This most recent Minotaur I space launch vehicle ordered by the Air Force will be launched from the Mid-Atlantic Regional Spaceport (MARS) facility at NASA’s Wallops Flight Facility at Wallops Island, Virginia in 2013.

“We are very pleased to continue to provide cost-effective military space missions for the U.S. Air Force,” said Mr. Ron Grabe, Orbital’s Executive Vice President and General Manager of its Launch Systems Group. “For the past 15 years, the Minotaur program has provided highly reliable and affordable launchers that combine government-owned propulsion systems with commercial rocket technology to support Department of Defense and other U.S. government space missions.”

The Minotaur I is a four-stage solid fuel space launch vehicle utilizing Minuteman rocket motors for its first and second stages, reusing government-owned motors that have been decommissioned as a result of arms reduction treaties. To date, Minotaur I has conducted 10 missions with a 100% success rate, delivering 32 satellites into orbit, while the entire Minotaur product line (see description below) has established a perfect 23-for-23 mission record.

The Enabler mission will be the fifth Minotaur I rocket to be launched from the MARS facility, following the TacSat-2, NFIRE, TacSat-3 and ORS-1 missions conducted from the Eastern Virginia launch site in 2006, 2007, 2009 and 2011, respectfully.

About Orbital’s Minotaur Product Line

Orbital’s Minotaur product line was originally developed under the U.S. Air Force’s Orbital/Suborbital Program (OSP). The initial five-year OSP contract was awarded to Orbital in 1997, followed by the 10-year OSP-2 contract received in 2002. The Minotaur product line includes both space launch vehicles and long-range suborbital vehicles for missile defense and other specialized missions.

Minotaur vehicles are the only proven launchers currently capable of supporting the Department of Defense’s evolving ORS launch requirements and are also specifically designed to be capable of launching from all major U.S. spaceports, including government and commercial launch sites in Alaska, California, Florida and Virginia. All Minotaur rockets share standardized avionics and subsystems, mature industrial processes and experienced personnel to make them reliable and cost effective.

The Minotaur I space launch configuration combines Orbital’s commercial launch vehicle technologies, including upper-stage rocket motors, structures, avionics and other elements, with government-supplied lower-stage rocket motors to create responsive, reliable and low-cost launch systems for U.S. government-sponsored spacecraft. It can place approximately 1,300 lbs. into low-Earth orbit.

In addition to the Minotaur I space booster, Orbital’s Minotaur product line also includes:

* Minotaur II – A three-stage suborbital rocket used as a target vehicle for testing U.S. missile defense systems and related missions.

* Minotaur III – A three-stage suborbital rocket that can deliver suborbital technology demonstration payloads of up to 6,500 lbs. or serve as a target vehicle for testing U.S. missile defense systems and similar missions.

* Minotaur IV – Introduced in 2010, the Minotaur IV uses retired Peacekeeper rocket motors, capable of launching U.S. government-sponsored satellites weighing up to 3,800 lbs. into low-altitude orbit and can also be configured as a three-stage suborbital booster. It has carried out five successful missions, including two suborbital flights for DARPA and three space launch missions.

* Minotaur V – An enhanced-performance version of the Minotaur IV space launch vehicle that will be used to launch government satellites into higher-energy orbits for missions related to space exploration and other activities beyond low-Earth orbit. Orbital will introduce the Minotaur V configuration in 2013 with the launch of NASA’s LADEE lunar spacecraft from MARS at Wallops Island, Virginia.

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