The infrared payload aboard the U.S. Air Force’s first Space Based Infrared System (SBIRS) satellite on June 21 transmitted its first image back to Earth and is functioning properly, prime contractor Lockheed Martin Space Systems said July 7.

The missile warning and missile defense satellite is now undergoing a payload checkout and calibration in preparation for operational acceptance next year, the Air Force said in a separate July 7 press release.

After a protracted development phase, the first SBIRS satellite was carried to geosynchronous orbit May 7 atop an Atlas 5 rocket. It joins two SBIRS payloads hosted on classified satellites in highly elliptical orbits. Sunnyvale, Calif.-based Lockheed Martin Space Systems is under contract to deliver a total of four geosynchronous satellites and four highly elliptical orbiting payloads.