The payload for a Geosynchronous Earth Orbit satellite of the U.S. Air Force's Space Based Infrared System has been delivered, Lockheed Martin reports.

The payload, delivered by Lockheed Martin and Northrop Grumman to Lockheed's satellite manufacturing facility, will be integrated with the SBIRS GEO-4 satellite bus in final assembly.

Lockheed Martin is the prime contractor for the satellite system, while Northrop is the payload provider.

The SBIRS program of the U.S. Air Force consists of multiple satellites to deliver timely, reliable and accurate missile warning and infrared surveillance information to the President of the United States, the Secretary of Defense, combatant commanders, the intelligence community and other key decision makers.

It supports the U.S. ballistic missile defense system, expands technical intelligence gathering and improves battlefield situational awareness.

The payload delivered, for the fourth GEO satellite, includes scanning and staring sensors, which give the satellite enhanced infrared sensitivity. Wide-area surveillance of missile launches and natural phenomena and observation of smaller areas with superior sensitivity will also be provided by the payload package.

"The completion of this payload is a critical milestone keeping us on schedule for delivering the SBIRS GEO-4 satellite to the Air Force in 2016," said Louie Lombardo, director of Lockheed Martin's SBIRS Follow-on Production program. "This payload delivery -- the third of four payload deliveries for the SBIRS SFP program in the past 15 months -- further demonstrates that SBIRS is in the regular cadence of full production."

The GEO-1 and GEO-2 satellites, which have been launched, have both received Air Force Space Command Operational Acceptance. GEO-3 recently completed acoustic testing and is currently undergoing thermal vacuum testing.

Lockheed Martin received an Air Force contract in June for full production of GEO-5 and GEO-6.