DULLES, Va., Sep 16, 2005 (BUSINESS WIRE) -- Orbital Sciences Corporation

-- NLS Contract for Pegasus and Taurus Small Launch Vehicles to
           Extend Company's Manifest Into the Next Decade --

    -- Company Estimates Total Value Could Exceed $200 Million Over
                    the Seven Year Contract Term --

Orbital Sciences Corporation (NYSE:ORB) announced today that it has been awarded a major contract by the National Aeronautics and Space Administration (NASA) to provide Pegasus(R) and Taurus(R) launch services for future NASA space missions over a seven-year period from 2005 to 2012. The contract was awarded under the NASA Launch Services (NLS) program, which allows the space agency to order small-, medium- and large-class launch services from several suppliers on an indefinite delivery/indefinite quantity (IDIQ) basis. The small-class missions covered under this contract are expected to extend the Pegasus and Taurus mission manifest into the early years of the next decade. Orbital estimates that six or seven launch vehicles will be required to support upcoming missions in the small-class mission segment through the end of 2012.

"We are very pleased that we were selected by NASA for this important space launch services contract," said Mr. David W. Thompson, Orbital's Chairman and Chief Executive Officer. "With their superb track record of repeated success, the Pegasus and Taurus rockets continue to be the vehicles of choice for NASA's upcoming small-satellite scientific missions over the next half decade or more."

The purpose of the NLS program is to supply launch services for scientific and space exploration missions to be conducted over the next seven years. Many of NASA's high-value scientific missions can be carried out by small-class satellites, which are best launched into orbit aboard dedicated, reliable and cost-effective small launch vehicles like Orbital's Pegasus and Taurus rockets.

The NLS contract represents the fifth time Orbital has been selected to be a long-term space launch services provider to NASA since the early 1990's. Orbital was previously awarded long-term launch services contracts under the space agency's Small Expendable Launch Vehicle Service program in both 1991 and 1998, under its Ultra-Lite Launch Vehicle Program in 1994 and under its Hyper-X hypersonic research program in 1996. These past contracts have involved launches of 29 NASA satellites and other payloads on 26 Pegasus and Taurus launch vehicles previously built, or being now constructed, by the company over a 15-year period.

In order to be qualified for this contract, Orbital was required to demonstrate that it met each of NASA's criteria laid out in the agency's initial NLS Request for Proposal. Among the minimum requirements was a record of having demonstrated at least one successful launch of the proposed vehicle configuration and ISO 9001 certification. In addition, NLS-qualified launch vehicles must be capable of achieving NASA's Risk Category 2 and 3 levels, which qualifies them to launch high-value payloads based on a demonstrated launch record of reliability. Orbital's Pegasus rocket has already achieved Category 3 certification and Taurus is also expected to reach the Category 2 and 3 levels within the term of the NLS contract.

The missions covered under this contract are expected to be conducted from several different launch sites, including the Western Range, located at Vandenberg Air Force Base (VAFB), California; the Eastern Range located at NASA's Kennedy Space Center, Florida; NASA's Wallops Flight Facility in Eastern Virginia and the Reagan Test Site at Kwajalein Atoll in the Marshall Islands. The operational flexibility of Orbital's air-launched Pegasus rocket and the mobile design of its Taurus rocket will allow both vehicles to meet the mission requirements at all launch sites.

About Orbital

Orbital develops and manufactures small space and rocket systems for commercial, military and civil government customers. The company's primary products are satellites and launch vehicles, including low-orbit, geosynchronous and planetary spacecraft for communications, remote sensing, scientific and defense 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 satellite-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.

SOURCE: Orbital Sciences Corporation

Orbital Sciences Corporation
Public and Investor Relations:
Barron Beneski, 703-406-5528
Beneski.barron@orbital.com