The U.S. Air Force Space Command's Space and Missile Systems Center awarded a $1.86 billion contract to Lockheed Martin Space Systems, Sunnyvale, Calif., for production of the fifth and sixth Space Based Infrared System geosynchronous missile-warning satellites. SBIRS is the next-generation strategic missile-warning system replacing the 1970s Defense Support Program constellation. SBIRS continuously delivers global, overhead, persistent, taskable infrared surveillance capabilities to meet 21st-century demands for early warning of missile launches, while simultaneously supporting other critical missions including missile defense, technical intelligence and battle space awareness. The SBIRS objective constellation consists of four GEO satellites, two highly elliptical earth orbit payloads and associated ground infrastructure. The fifth and sixth satellites will replenish on-orbit satellites in the constellation in order to maintain the required operational mission capabilities. The SBIRS program is led by the Infrared Space Systems Directorate at the U.S. Air Force Space and Missile Systems Center. The contract award realized more than $1 billion in savings as a result of the block-buy contracting approach and a range of planned production and management efficiencies, according to an Air Force announcement.