Lockheed Martin [LMT] in June delivered the third of four highly elliptical earth orbit (HEO) satellite payloads contracted by the Air Force as part of the Space Based Infrared System (SBIRS) missile warning satellite constellation, according to a company statement.

The delivery of the HEO-3 payload is the first major delivery from the SBIRS follow-on production contract, which also includes the third and fourth SBIRS satellites and an additional HEO payload, according to Air Force Space Command (AFSPC). Before being shipped, the HEO-3 payload also completed thermal vacuum chamber testing March 30. Thermal vacuum chamber testing demonstrates that the sensor’s performance met or exceeded its predecessor, HEO-2.

The HEO-3 payload is a high-tech, space-based sensor capable of detecting missile launches around the globe. The SBIRS program enhances global missile launch detection capability, supports the United States’ ballistic missile defense system, expands the country’s technical intelligence gathering capacity and bolsters situational awareness for warfighters on the battlefield.

The SBIRS architecture includes a mix of satellites in geosynchronous earth orbit (GEO) orbit, hosted payloads in HEO orbit and ground hardware and software.

AFSPC May 17 declared the GEO-1 satellite operational and recommended Integrated Tactical Warning and Attack Assessment (ITW/AA) certification to U.S. Strategic Command (STRATCOM). The Air Force’s second SBIRS GEO satellite, GEO-2, was successfully launched March 19 and has been delivering data as part of on-orbit testing. Lockheed Martin in March also received contracts to procure long-lead items as part of geosynchronous earth orbit (GEO) payloads five and six.

Lockheed Martin Vice President of Overhead Persistent Infrared operations said in a statement the company will now focus on completing the HEO-4 payload and GEO payloads three and four.