Orbital Sciences Corporation
today announced that it has completed the full-scale "pathfinder" ground
operations of the Minotaur IV space launch vehicle in preparation for its
inaugural flight that is currently scheduled to take place in early 2009.
The ground testing activities included the assembly of a full-scale
Minotaur IV rocket, using inert rocket motors and flight-qualified
structures to fully validate all interfaces with the booster, ground
support equipment and facility structures. The pathfinder operations were
overseen by representatives from the U.S. Air Force organizations that will
play critical roles in the Minotaur IV launch operations. These include
the U.S. Air Force Space and Missile Systems Center, the U.S. Air Force
Space and Development Test Wing, and 30th Space Wing based at Vandenberg
Air Force Base (VAFB) in California. The Spaceport Systems International
launch pad at VAFB will be the launch site for all three Minotaur IV
missions planned in 2009.

"The completion of our pathfinder ground operations test is a major step
forward as we proceed toward the inaugural launch of the Minotaur IV launch
vehicle," said Mr. Lou Amorosi, Orbital's Vice President with
responsibility for its entire Minotaur launch vehicle product line. "In
conjunction with our customers and partners that will play vital roles
during actual launch operations, we are taking a very methodical and
comprehensive approach to ensuring that all aspects of the launch vehicle
preparations, ground operations and range safety systems are meticulously
planned, rehearsed and reviewed."

The completion of the pathfinder testing activities is a critical milestone
in the development of the Minotaur IV launch vehicle. It serves as a
rehearsal of all hazardous lifting operations, a fit-check for all vital
rocket and ground interfaces, a final test of the mission's ground support
equipment, and a checkout of vehicle integration procedures. The extensive
pre-launch activities also enhance training of the launch crew and facility
personnel.

Prior to beginning the pathfinder operations, procedures for all hazardous
operations were approved by range safety officials and the ground support
equipment involved in the procedures was proof-tested to range safety
standards prior to use. The pathfinder operation was the final test of new
Minotaur IV structures, which had recently been fully-qualified to
military-standard levels.

During the pathfinder, the various vehicle stages and components were
transported, assembled and stacked at the launch site. Once the vehicle
was fully assembled, a day-of-launch shelter rollback was rehearsed.
Subsequent to those operations, abort operations were also rehearsed and
timed before the vehicle was de-stacked and transported back to the
integration facility.

The ground operations also included rehearsal of spacecraft encapsulation
procedures within the launch vehicle fairing. The Minotaur IV design
provides for separate spacecraft encapsulation, which is an enabling
procedure for Operationally Responsive Space (ORS) missions, by
streamlining the time and sequence of spacecraft encapsulation. Spacecraft
can be selected for launch, mated, encapsulated and transported to the
launch site independent of other launch vehicle or range operations.