Orbital Sciences Corporation has announced that NASA has ordered four space launch vehicles, including two Pegasus and two Taurus rockets, for U.S. government scientific satellite missions scheduled to be launched over a two-year period beginning in 2006.

The orders were placed under the Small Expendable Launch Vehicles Services (SELVS) contract that was awarded to Orbital by NASA’s Kennedy Space Center in 1998.

The two new Pegasus vehicles will be used to launch the satellites designated for NASA’s Space Technology-8 (ST-8) and Small Explorer-10 (SMEX-10) missions. The two Taurus missions are scheduled to launch NASA satellites that Orbital is currently developing and manufacturing at its Dulles, VA facility.

The first of the two new Taurus rockets will launch the GLORY satellite for NASA’s Goddard Space Flight Center. The second Taurus rocket will launch the Orbiting Carbon Observer satellite for the Jet Propulsion Laboratory.

With these new launch vehicle orders, NASA is continuing a 12-year relationship with Orbital for Pegasus and derivative rockets, which began in 1991. During this time, the space agency has purchased 25 Pegasus, Taurus and related launch vehicles for a wide range of Earth and space science and technology demonstration missions. Fourteen of these launches have been carried out to date, while another 11 are planned from 2004 to 2008.

“Orbital is very pleased with NASA’s continued commitment to our space launch vehicle products,” said Mr. David W. Thompson, Orbital’s Chairman and Chief Executive Officer. “We look forward to continuing the excellent working relationship that our launch vehicle team has established with its NASA counterparts. Together, our shared goal is to reliably support the scientific community’s use of small satellites for highly productive Earth and space science investigations.”