Orbital Sciences Corporation announced today that the
company’s missile defense interceptor boost vehicle, being developed
and manufactured for the U.S. Missile Defense Agency’s (MDA)
Ground-based Midcourse Defense (GMD) system, carried out its third
fully successful test flight late yesterday. As part of MDA’s
Integrated Flight Test-13b (IFT-13b), Orbital’s GMD interceptor
vehicle, which carried a mock kill vehicle to simulate actual mission
operations, was launched from a silo at approximately 9:23 p.m. (EST)
on January 26, 2004. The IFT-13b flight originated from the Reagan
Test Site on Kwajalein Atoll in the Marshall Islands, located in the
mid-Pacific Ocean.

Following preliminary post-flight analysis of the data collected
from the mission, Orbital confirmed that all primary objectives for
the vehicle’s third launch were achieved. The objectives for the
mission included the second demonstration of the vehicle’s silo-launch
capabilities, the verification of the vehicle’s design and flight
characteristics while carrying a simulated kill vehicle, and further
confirmation of the planned performance of its guidance, control and
propulsion systems.

Orbital’s GMD boost vehicle is a three-stage rocket based on
flight-proven hardware that has flown over 45 times on 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.

“We are very pleased that our GMD interceptor vehicle successfully
carried out its role in the integrated flight test,” said Mr. Ron
Grabe, Executive Vice President and General Manager of Orbital’s
Launch Systems Group. “We have continued to meet the progressively
more challenging test conditions for our vehicle, which will lead to
more extensive testing and operational deployment later this year.”

The successful launch of the GMD boost vehicle was the company’s
first space mission in 2004 following two consecutive years of fully
successful missions encompassing 26 rocket launches and satellite
deployments. Orbital is expecting 2004 to be one of the busiest years
in its history, with approximately 20 major space missions and up to
20 additional system deliveries to be completed for a wide range of
military, scientific and commercial missions for domestic and
international customers.

Orbital’s space launch vehicles, missile defense interceptors and
related suborbital rockets are primarily 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 low altitude
orbits above 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, geostationary and planetary spacecraft for
communications, remote sensing and scientific missions. 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.