Satellite Based on Company’s STAR-2 Platform on Track for Launch in July

Orbital Sciences
Corporation announced today that the N-STAR c geosynchronous (GEO)
communications satellite built by a Lockheed Martin/Orbital team for NTT
DoCoMo, Inc. of Japan has arrived at the launch site in Kourou, French Guiana.
Over the next several weeks, the N-STAR c spacecraft will undergo final pre-
launch testing in preparation for a launch in early July aboard an Ariane 5
rocket. The N-STAR c satellite will operate in S-band frequencies with a C-
band feeder link from its orbital location at 136 degrees East longitude. The
spacecraft is optimized for a 10-year on-orbit life and will provide mobile
telephony and data transfer services to Japan and its surrounding waters.

The customer for the N-STAR c satellite, NTT DoCoMo is Japan’s premier
mobile communications company. It provides wireless voice and data
communications to tens of millions of subscribers. NTT DoCoMo is the creator
of W-CDMA air interface technology, the new de facto global industry standard
for mobile communications, as well as the groundbreaking mobile “i-mode”
service.

For the N-STAR c program, Orbital is teamed with Lockheed Martin
Commercial Space Systems of Newtown, Pennsylvania. Lockheed Martin is serving
as the prime contractor and communications payload supplier. Orbital is
responsible for providing the space system, including the satellite bus and
related ground system, as well as procuring the launch vehicle and conducting
initial satellite operations. The final pre-shipment integration and testing
process was recently completed by a team of Orbital and Lockheed Martin
engineers at Lockheed Martin’s facilities in Newtown.

Orbital’s GEO communications satellites are based on the company’s STAR-1
and STAR-2 standard platforms, which are able to accommodate most types of
commercial communications payloads. For many applications, the lighter
weight, affordable STAR design is an attractive alternative to the larger,
more costly GEO satellites offered by the industry’s traditional suppliers.
The STAR satellites are smaller and significantly less expensive to
manufacture and launch. They are a perfect fit for customers in the early
stages of building their business or established companies that require
incremental capacity for their network.

Orbital is one of the world’s leading developers and manufacturers of
affordable space systems for commercial, civil government and military
customers. The company’s primary products include low-orbit, geostationary and
planetary spacecraft for communications, scientific and remote sensing
missions; ground- and air-launched rockets that deliver satellites into orbit;
and missile defense boosters that are used as target and interceptor vehicles.
Orbital also offers space-related technical services to government agencies
and develops and builds satellite-based transportation management systems for
public transit and public works agencies, as well as private vehicle fleet
operators.

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

CONTACT: Barron Beneski, Public and Investor Relations, of Orbital
Sciences Corporation, +1-703-406-5528, or Beneski.barron@orbital.com