Orbital Sciences
Corporation announced today that the Galaxy XII geosynchronous
orbit (GEO) communications satellite the company built for PanAmSat
Corporation was successfully launched aboard an Ariane 5 rocket
on Wednesday, April 9, 2003. The mission originated from the Arianespace
launch complex in Kourou, French Guiana at approximately 6:52 p.m. (EDT) and
the Galaxy XII satellite was deployed into a transfer orbit about 39 minutes
later. Initial communications with the satellite have been established and it
is performing as expected in the early stages of the mission. The Galaxy XII
satellite is the fifth GEO spacecraft Orbital has launched, each of them
carried aboard an Ariane rocket.

Over the next several days, Galaxy XII will perform a series of orbit-
raising “burns” of its on-board rocket engine to achieve a circular orbit
approximately 22,300 miles above the Earth. For several weeks afterward, a
team of Orbital and PanAmSat engineers will conduct a comprehensive series of
tests to ensure the spacecraft’s readiness for its final hand-over to
PanAmSat, which is currently scheduled to occur in late June.

The Galaxy XII satellite will operate in C-band frequencies from its
orbital location at 74 degrees West longitude. The spacecraft is optimized
for a 15-year design life and will provide capacity for PanAmSat’s satellite
network over the continental United States, Alaska and Hawaii.

In the past several years, Orbital has firmly established itself as a
primary supplier in the world market for GEO communications satellites. The
company’s GEO satellites are based on the STAR(TM) family of smaller GEO
satellite platforms, which are able to accommodate most types of commercial
communications payloads. For many applications, the 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 are
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 wish to replace or add capacity to their network.

About PanAmSat

PanAmSat Corporation is the premier provider of global video and data
broadcasting services via satellite. Operating a global network of 21 in-orbit
spacecraft with more than 800 transponders and seven technical facilities on
the ground, the company reaches 98 percent of the world’s populations with
entertainment and information delivered through cable television systems, TV
broadcast affiliates, direct-to-home TV operators, Internet service providers,
and telecommunications companies. More information about PanAmSat can be found
at http://www.panamsat.com

About Orbital

Orbital develops and manufactures small space systems for commercial,
civil government and military customers. The company’s primary products are
spacecraft and launch vehicles, including low-orbit, geostationary and
planetary spacecraft for communications, remote sensing and scientific
missions; ground- and air-launched rockets that deliver satellites into orbit;
and missile defense boosters 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

Note to editors:

A high-resolution (300+ d.p.i.) artist rendering of the Galaxy XII
satellite in orbit is available on Orbital’s web site at:
http://www.orbital.com/NewsInfo/Images/GEO/

A Fact Sheet on the three GEO satellites Orbital is building for PanAmSat
is also available at: http://www.orbital.com/NewsInfo/Publications/

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