WASHINGTON — The second satellite in the U.S. Air Force’s next-generation missile warning constellation, the Space Based Infrared System (SBIRS) GEO-2, has achieved “operational acceptance” some five months earlier than expected, according to a Nov. 25 press release from the service.

The satellite launched March 19.

Air Force officials said the satellite was originally slated to enter its trial service period after 12 months of on-orbit testing, but based on lessons learned during testing of the SBIRS GEO-1 spacecraft they were able to truncate that schedule. 

“The combined test team was able to improve on the original schedule by five months and GEO-2 entered its trial period Oct. 21, 2013, with no liens,” the release reads. “Overall, the GEO-2 satellite’s performance matches that of GEO-1 and in some cases exceeds it.”

Air Force Space Command quietly declared SBIRS GEO-1 operational May 17, two years after its launch. The Air Force has attributed GEO-1’s lengthy commissioning period to an on-board communications issue that was corrected via a software upload.

Built by Lockheed Martin Space Systems of Sunnyvale, Calif., SBIRS GEO-1 was launched May 7, 2011, from Cape Canaveral Air Force Station, Fla., atop a United Launch Alliance Atlas 5 rocket. The Air Force launched its companion spacecraft, SBIRS GEO-2, in March. 

When fully deployed, the SBIRS system will include four dedicated satellites in geosynchronous orbit, infrared sensors hosted on classified satellites in highly elliptical orbits, and a network of ground stations to receive, process and distribute the data. SBIRS is the replacement for the Defense Support Program constellation of satellites that have provided missile warning since the early 1970s.

The third geosynchronous SBIRS satellite, GEO-3, is expected to launch in 2015, with the fourth to follow about a year later.

In 2012, Congress authorized the Air Force to spend $3.9 billion to purchase the fifth and sixth satellites, called GEO-5 and GEO-6. Lockheed Martin has already begun ordering their components and is expected to deliver the satellites in 2019.

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Mike Gruss is a senior staff writer for SpaceNews. He joined the publication in January 2013 to cover military space. Previously, he worked as a reporter and columnist for The Virginian-Pilot in Norfolk, Va. and The Journal Gazette in Fort Wayne, Ind. He...