The U.S. Air Force is nearing completion of a plan to restock its missile-warning satellite system, according to a key service official.

The Air Force’s Space Based Infrared System (SBIRS) program, whose prime contractor is Lockheed Martin [LMT], is in the midst of acquiring six geosynchronous Earth orbit (GEO) satellites and four sensors on classified host satellites in highly elliptical orbit (HEO). For the past two years, the Air Force has been studying what comes after those spacecraft.

Lockheed Martin’s SBIRS GEO-1 payload is loaded onto an Air Force C-5 in 2011. Photo: Lockheed Martin.
Lockheed Martin’s SBIRS GEO-1 payload is loaded onto an Air Force C-5 in 2011. Photo: Lockheed Martin.

“The Air Force has a need to replenish and/or augment … SBIRS on-orbit assets to provide continuing capabilities for strategic missile warning, theater missile warning, missile defense, battlespace awareness, technical intelligence and civil/environmental monitoring,” said Lt. Gen. Sam Greaves, commander of Air Force Space and Missile Systems Center and Air Force program executive officer for space. “The Air Force … is working toward a follow-on acquisition strategy approval in fall 2016.”

GEO-1 and GEO-2 were launched in 2011 and 2013, respectively. GEO-3 is scheduled to lift off in October, followed by GEO-4 in 2017. GEO-5 and GEO-6, which will replace the first two satellites, are to be available for launch in 2020 and 2021.

HEO-1 and HEO-2, which achieved orbit in 2006 and 2008, respectively, are to be replaced by HEO-3, which was launched in 2014, and HEO-4, which is being integrated onto its host satellite.