WASHINGTON — Lockheed Martin Space Systems of Sunnyvale, Calif., will continue ordering parts for two missile warning satellites and start work on four next-generation navigation satellites under three contracts worth more than $400 million combined, the U.S. Defense Department announced Feb. 21.

The majority of the money, $284 million, will go toward the fifth and sixth satellites in the Space Based Infrared System (SBIRS) for missile warning.

Operated by the U.S. Air Force, SBIRS will consist of four dedicated satellites in geosynchronous orbit plus sensors hosted aboard classified satellites in highly elliptical orbits. Lockheed Martin’s current SBIRS contract covers four dedicated satellites and long-lead items for two more; four elliptical-orbit infrared sensors; and the ground segment.

The work announced Feb. 21 includes parts for the fifth and sixth satellites in geosynchronous orbit. Lockheed Martin began ordering components and performing engineering work for these craft under an $82 million contract awarded in September.

Congress has authorized the Air Force to spend $3.9 billion starting this year to buy those satellites, called GEO-5 and GEO-6.

Lockheed Martin also will begin work on the fifth through eighth next-generation GPS 3 satellites. The GPS 3 satellites are expected be more accurate and less vulnerable to jamming than preceding generations of GPS craft.

“The GPS 3 program will affordably replace aging GPS satellites while improving capability to meet the evolving demands of military, commercial and civilian users.” Mark Valerio, vice president and general manager of Lockheed Martin’s military space business, said in a statement.

One of the GPS 3 contracts is a $62 million fixed-price contract for unidentified work for the fifth and sixth satellites. The other contract, valued at $58 million, is to begin ordering parts for the seventh and eighth satellites.

Valerio said the fixed-price contract allows Lockheed Martin to save money by reducing program oversight, labor hours and unnecessary meetings, and by standardizing parts and processes.

Christina Greer, a spokeswoman for Air Force Space and Missile Systems Center in El Segundo, Calif., said via email that the service hopes to have full-scale production contracts for the two missile warning satellites and the four GPS 3 craft by the end of 2013.

Mike Gruss is a senior staff writer for SpaceNews. He joined the publication in January 2013 to cover military space. Previously, he worked as a reporter and columnist for The Virginian-Pilot in Norfolk, Va. and The Journal Gazette in Fort Wayne, Ind. He...