Orbital Set to Launch New OSP Rocket For U.S. Air Force on January 14

Orbital Sciences Corporation (NYSE: ORB – news) announced today that it is in final preparations to launch the
U.S. Air Force’s Orbital/Suborbital Program (OSP) space launch vehicle on Friday, January 14, 2000 from Vandenberg Air Force Base (VAFB),
California. The OSP rocket uses a combination of deactivated Minuteman II rocket motors as the vehicle’s first and second stages and technology from
Orbital’s Pegasus XL rocket for the vehicle’s third and fourth stages, and for guidance and control support. Orbital is under contract to the Air Force to
perform all integration, testing and launch operations for the program. The Air Force’s primary goal for this launch is to validate the OSP rocket’s space
launch capability. The launch schedule is subject to final preparations and testing, as well as acceptable weather conditions at VAFB at the time of the
launch. For more information about the OSP launch vehicle, visit http://www.losangeles.af.mil/SMC/PA/Fact_Sheets/minotaur_fs.html

The launch of the OSP rocket is set for 7:04 p.m. (PST) with an available launch window that extends from 6:54 p.m. to 9:54 p.m. The OSP rocket will
carry multiple payloads on this mission, including the Joint Air Force Academy/Weber State University (JAWSAT) multi-payload adapter. The four
payloads aboard JAWSAT are the U.S. Air Force Academy’s FalconSat, Arizona State University’s ASUSAT (a student-built payload that has been
sponsored by Orbital from its inception through launch), Stanford University’s OPAL satellite and the Air Force Research Laboratory’s Optical Calibration
Sphere Experiment. Two experiments also attached to the multi-payload adapter are NASA Marshall Space Flight Center’s Plasma Experiment Satellite
and Weber State University’s Attitude Controlled Platform. For more information about the mission’s payloads, visit http://cast.weber.edu/jawsat

The launch of the OSP rocket will be Orbital’s third space launch in the last six weeks. On December 4, Orbital’s Pegasus rocket successfully launched
seven ORBCOMM satellites into their targeted low-altitude orbit, while on December 19, the company’s Taurus® rocket successfully launched The
Republic of Korea’s KOMPSAT satellite and NASA’s ACRIMSAT spacecraft, which was also built by Orbital. In addition to these space launches,
Orbital’s Remote Manipulator System, also known as the “Canadarm,” played a key role in the successful servicing mission of the Hubble Space
Telescope performed by U.S. astronauts aboard the Space Shuttle in late December 1999.

Orbital is one of the largest space technology and satellite services companies in the world, with 1999 revenues targeted to exceed $900 million. The
company, which is headquartered in Dulles, Virginia, employs over 5,200 people at its major facilities in the United States, Canada and several overseas
locations. Orbital is the world’s leading manufacturer of low-cost space systems and products, including satellites, launch vehicles, electronics and sensors,
satellite ground systems and software, and satellite-based navigation and communications products. Through its ORBCOMM and ORBIMAGE affiliates
and ORBNAV subsidiary, Orbital is also a pioneering operator of satellite-based networks that provide data communications, high-resolution imagery and
automotive information services to customers all around the world.