WASHINGTON — The U.S. Air Force awarded Lockheed Martin Space Systems of Sunnyvale, California, a contract modification worth $1.86 billion to complete construction of the fifth and sixth satellites in its new missile warning constellation, the service announced June 24.

The contract modification follows two earlier contracts to begin work on the Space Based Infrared System satellites. Those preliminary contracts, awarded in February 2013 and September 2013, were valued at $284 million and $42 million, respectively.

In a press release, the Air Force said it is saving $1 billion by purchasing the two SBIRS satellites at once. Block buys enable contractors to be more efficient by ordering components in bulk and avoiding breaks in production.

“We saved hundreds of millions by relentlessly pursuing efficiencies,” Col. Mike Guetlein, the Air Force’s SBIRS production program manager, said in a prepared statement. “We eliminated unnecessary layers of program oversight and contract reporting, restructured our test program, and streamlined the production schedules.”

In addition to satellite construction, the contract modification covers work on the SBIRS ground system and related updates, as well as satellite testing, launch-related activity, early on-orbit operations and related contractor support, the Defense Department said in a June 24 contract announcement. The work is expected to be completed by Sept. 30, 2022, the announcement said.

Currently the Air Force operates two dedicated SBIRS satellites in geosynchronous orbit as well as two SBIRS infrared sensors aboard classified satellites in highly elliptical orbit. The fully deployed system, which replaces the venerable Defense Support Program missile warning satellites, will include four dedicated satellites in geostationary orbit.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...