-- Company Well Positioned to Continue Support for Air Force

                          Rocket Programs --

DULLES, Va.March 27, 2008--Orbital Sciences Corporation (NYSE:ORB) announced today that the U.S. Air Force Space and Missile Systems Center recently awarded the company a seven-year task order contract to provide target vehicles and related support for the Sounding Rockets Program-3 (SRP-3). Orbital was one of four companies selected for contracts that qualify them to compete for up to $250 million in launch services under the U.S. Government's indefinite delivery/indefinite quantity (IDIQ) procurement approach. Orbital's Launch Systems Group, which is responsible for the company's space and suborbital launch vehicle design, production and operations, will carry out the SRP-3 activities at company facilities in Chandler, Arizona.

The Air Force's Sounding Rockets Program supplies target, testbed and special-purpose rockets that are used by the Air Force, other U.S. Department of Defense agencies and NASA. The SRP-3 contract is a follow-on to the Air Force's SRP-1 and SRP-2 contracts under which Orbital competed for and won task orders to provide the Navy Theater Wide (NTW) target vehicles, the Quick Reaction Launch Vehicle-1 (QRLV-1), Quick Reaction Launch Vehicle-2 (QRLV-2), the atmospheric intercept test-1 (ait-1) vehicle, the Patriot Target Vehicles (PTV) and NASA's Abort Test Boosters (ATB's).

"This contract places us in a strong competitive position to win additional missile business, especially given our successful efforts under the SRP-1 and SRP-2 contracts in securing new tasks and our outstanding track record of executing missions," said Mr. Ronald J. Grabe, Orbital's Executive Vice President and General Manager of its Launch Systems Group.

Orbital's suborbital rockets frequently combine U.S. Government-supplied surplus ICBM booster assets with commercial motors and subsystems to meet military requirements in a highly cost-effective, low-risk manner. Orbital's wide variety of suborbital launch configurations have established a long track record of reliability and accuracy to meet the needs of U.S. military customers.

About Orbital

Orbital develops and manufactures small 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 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 offers space-related technical services to government agencies and develops and builds software-based transportation management systems for public transit agencies and private vehicle fleet operators.

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

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

    SOURCE: Orbital Sciences Corporation