The U.S. Air Force has awarded Lockheed Martin Corp. a $1.4 billion contract to manufacture, integrate and test a fourth Advanced Extremely High Frequency communications satellite, the military branch announced Friday.

The AEHF 1 satellite. Credit: Lockheed Martin

The contract award is the next step in the Air Force's effort to sustain its military satellite communications network following the cancellation in 2009 of the next-generation Transformational Satellite Communications System, or TSAT.

At the time of the TSAT program's cancellation, the Pentagon announced it would procure two additional AEHF satellites to join the three craft already in development.

This week's announcement is the first AEHF satellite ordered by the Air Force since the end of the TSAT program.

According to the Air Force, the AEHF 4 spacecraft is expected to be ready for launch in 2017. It is unclear when the Air Force could order additional AEHF satellites, but Lockheed Martin officials have said they hope to receive the go-ahead soon to acquire long-lead parts for more spacecraft.

A Lockheed Martin spokesperson did not respond to questions about the procurement of components for additional AEHF platforms. Lockheed Martin previously got approval to start buying parts for AEHF 4.

The Air Force struck a $182 million deal with Boeing Co. in August for start-up activities and procurement of long-lead items for an extra Wideband Global SATCOM spacecraft.

The AEHF satellites are designed to operate in a wartime environment, beaming high-priority messages and data between military commanders and the nation's civilian leadership. AEHF spacecraft are hardened to withstand the demands of nuclear and electronic warfare.

The program replaces the five-satellite Milstar constellation. A single AEHF spacecraft has more capacity than the entire Militar fleet combined, according to the Air Force.

AEHF 1 blasted off in August on an Atlas 5 rocket, but a propulsion system failure shortly after launch forced the satellite to use smaller thrusters to move to its operational orbit more than 22,000 miles above Earth. The spacecraft is not expected to reach geosynchronous altitude until August 2011.

The anomaly also prompted the Air Force to delay the planned launch of the second AEHF satellite from early 2011 until 2012. AEHF 2 is now in storage, while AEHF 3 is expected to finish production next year.