The U.S. Air Force has awarded Lockheed Martin Space Systems of Sunnyvale, California, a $20 million contract modification for work on the fifth and sixth satellites in the Space Based Infrared System for missile warning, according to a May 20 announcement from the Pentagon.

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

The money from the modification will be used for planning and production parts including hinges, valves, structures and special test equipment, according to the announcement. 

The SBIRS system consists of dedicated satellites in geosynchronous orbit complemented by infrared missile warning sensors aboard classified satellites operating in highly elliptical orbit, or HEO.

Lt. Gen. Ellen M. Pawlikowski, commander of the Los Angeles-based Air Force Space and Missile Systems Center, wrote in the September edition of Air & Space Power Journal that the service plans to step up GEO-5 and GEO-6 staffing levels as GEO-3 and HEO-4 staffing levels are coming down. 

According to a March 12 report from the Government Accountability Office, the total cost of the SBIRS program is nearly $19 billion.