Company On Track to Meet U.S. Missile Defense Agency’s Deployment Requirement for Up To 20 Interceptor Boosters by the End of 2005, Plus Additional Vehicles for Robust Test Program

Orbital Sciences Corporation announced that it supplied
the first interceptor boost vehicle for the U.S. Missile Defense
Agency (MDA)’s Ground-based Midcourse Defense (GMD) system that was
installed into an underground silo at Fort Greely, Alaska yesterday,
July 22, 2004. The company also stated that it has delivered several
other Orbital Boost Vehicle (OBV) interceptors that are scheduled for
emplacement over the next several weeks and is currently producing
additional vehicles at its facilities at Vandenberg Air Force Base
(VAFB), California. The company is currently on schedule to meet MDA’s
goal of deploying up to 10 operational interceptors by the end of 2004
and up to 20 operational interceptors by the end of 2005. The current
plan calls for 16 OBVs to be deployed at Fort Greely and up to four
OBVs to be deployed at VAFB by the end of next year. Orbital will also
supply OBV interceptor rockets and several target vehicles to support
the robust GMD testing program MDA has planned for the next several
years.

“This is a very proud moment for all of Orbital’s employees,”
stated Mr. Ron Grabe, Executive Vice President and General Manager of
its Launch Systems Group. “To have Orbital’s expertise in interceptor
vehicle technology play such a key role in helping defend the United
States from the threat of ballistic missile attack is a true honor. We
place the utmost importance on our role in the GMD program and regard
it as our highest calling.”

Over the next several weeks, the three-stage OBV, which will carry
an exoatmospheric “kill vehicle” designed to collide with and destroy
a hostile long-range missile in the midcourse phase of its flight,
will be integrated with the Defense Department’s network of early
warning sensors, long-range radars, and command and control, battle
management and communications systems. When operational, the GMD
system will be operated by the U.S. Northern Command and will be an
integral part of the planned multi-layer ballistic missile defense
system designed to detect, intercept and destroy ballistic missiles to
protect the U.S. homeland, deployed U.S. troops and nations.

Orbital’s GMD boost vehicle is a three-stage rocket based on
flight-proven hardware that has flown about 50 times on previous
missions carried out by the company’s Pegasus®, Taurus® and
Minotaur space launch vehicles. Orbital is developing, manufacturing
and testing interceptor vehicles under a multi-year contract from The
Boeing Company, MDA’s lead system integrator for the GMD
program.

About Orbital

Orbital’s space launch vehicles, missile defense interceptors and
related suborbital rockets are primarily designed and produced at the
company’s engineering and manufacturing facility in Chandler, Arizona
and its vehicle assembly and integration facilities at Vandenberg Air
Force Base in California. The launch vehicles are used by commercial
and government customers to deliver small satellites into orbits about
the Earth and in missile defense systems, both as threat-simulating
target vehicles and as interceptor boosters for U.S. national defense
systems.

In addition to its launch vehicle systems, Orbital’s other primary
products are satellites and related space systems, which are also used
by commercial, civil government and military customers. These products
include low-orbit, geosynchronous and planetary spacecraft for
communications, remote sensing, scientific missions and national
security. In addition, Orbital 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.